EUROISMAR 2019

The application of Diffusion Ordered NMR Spectroscopy has vastly increased in the last years, which illustrates the benefits of monitoring diffusion in solution NMR. Consequently much effort has been ventured to improve the application of diffusion measurements in NMR [1]. In this work we introduce a pulse sequence that enables the spectroscopist to perform DOSY experiments in a matter of tens...

Elena Shanina, Sakonwan Kuhaudomlarp^‡, Priscila Gomes^†, Eike Siebs^ƒ, Alexander Titz^ƒ, Didier Rognan^†, Anne Imberty^‡, and Christoph Rademacher
Max Planck Institute of Colloids and Interfaces, Potsdam, Germany;
^‡ Univ. Grenoble Alpes, CNRS, CERMAV, Grenoble,...

¹²⁹Xe is classically hyperpolarized using the well-established spin exchange optical pumping (SEOP) method. At optimal conditions and using ¹²⁹Xe enriched gas, SEOP can provide up to 3.6L/h of xenon hyperpolarized to 30%, enabling routine clinical ¹²⁹Xe MRI [1]. Besides SEOP, sublimation-DNP was proposed as an alternative technique to produce hyperpolarized...

Nanodiamonds (NDs) are a subject of increased application interest based on the possibilities of their use in medical imaging [1] and as drug delivery systems [2, 3]. Fluorescent NDs are addressed as they emit single-photon luminescence due to a number of optically sensitive paramagnetic defects, particularly nitrogen-vacancy centres. The knowledge on how the defect types and distribution in...

Chemically induced dynamic nuclei polarization(CIDNP) is one of the hyperpolarization methods allowing to enhance sensitivity of NMR. The CIDNP effect, which occurs in photochemical reaction, is called photo-CIDNP effect. In this research flavin-binding LOV domain, which is a blue light receptor, can receive an electron from a short distance(appr. 11Å) tryptophan. This electron is the core of...

Signal Amplification By Reversible Exchange (SABRE) is a method based on the transfer of parahydrogen (p-H₂) polarization to the substrate nuclei due to the constant exchange of p-H₂ and ligands over metallic Ir center of metal-organic complex. Generated levels of polarization provide the higher signal of the ligand. In the experiments, when SABRE process occurs in high...

In this contribution, we present a simple analytical fitting approach based upon a power-law model of the segmental orientation autocorrelation function (OACF), by the way of which an effective power-law time scaling exponent and the amplitude of the OACF can be estimated from multiple-quantum (MQ) NMR data at any given temperature [1]. This obviates the use of the time-temperature...

Chloride salts have wide applications in pharmaceuticals, whether they are used for isolating and purifying the active pharmaceutical ingredients, or for providing more stability and/or solubility to the drugs. ³⁵Cl nucleus has a 75% natural abundance and it is quadrupolar, with a nuclear spin I=3/2. In many organic compounds where it is covalently bound, the ³⁵Cl nucleus...

Double Quantum NMR is a well-established method to study spatial proximities and local molecular dynamics in solid samples. In many cases, more or less restricted local dynamics of polymer chains has been analyzed. Here we studied the local packing of phosphate groups during the crystallization of precise polyethylene obtained from acrylic diene metathesis (ADMET) polycondensation with...

Most materials are heterogeneous on the millimeter resolution of magnetic resonance imaging (MRI) in the sense that they are comprised of multiple microscopic domains with different chemical and diffusional properties. Consequently, the measured MRI signal on the voxel scale is highly unspecific as it originates from the average of the signals arising from these domains. However,...

An unexpected great challenge in dDNP [1] has recently emerged with the use of ultra-shielded DNP magnets; the preservation of hyperpolarization during transfer from one ultra-shielded magnet to the other in ultra-low field regions, as magnetization not only relaxes but can be wiped-out in a non-adiabatic process.

We have recently proposed the design of a fluid path for dDNP [2] based on a...

Short-lived and low-abundance enzyme intermediate complexes represent a mainstream of transient protein complexes in enzyme catalysis and signal transductions. Many transient and unstable protein intermediate complexes are generated in real-time reactions or non-equilibrium conditions, however, resonance assignments of these unstable complexes are a challenge and structural determination of...

In Ti-based Ziegler-Natta catalysts (ZNCs), disagreements exist concerning which lateral surface of the MgCl$_2$ support adsorbs Ti species so as to be an active site for the catalysis of polymerization. In the present paper, we investigated the local structure of TiCl$_4$ adsorbed onto the surface of MgCl$_2$ by $^{47,49}$Ti solid-state nuclear magnetic resonance (NMR) spectra at 21.8 T along...

The automation of NMR structure determination remains a significant bottleneck towards increasing the throughput and accessibility of NMR as a structural biology tool to study proteins. The chief barrier currently is that obtaining NMR assignments at sufficient levels of completeness to accurately define the structures by conventional methods requires a significant amount of spectrometer time...

It is known that cobalt exhibits polymorphism: it exists in both hcp and fcc phases. Synthesis method and other thermodynamic conditions are known to play a role in determining the phase composition of cobalt nanoparticles. In this work, we have studied the phase composition of the cobalt nanoparticles synthesized using two different solvents (water) and ethanol. XRD measurements confirm the...

NMR is a primary method of measurement that provides quantitative results without the need of a standard of the same measurand. Amongst different procedures for quantification of organic compounds by NMR, the International Bureau of Weights and Measures (BIPM) encourages the use of internal standard (IS) NMR as it presents less sources of errors and smaller uncertainties. The use of a...

NMR spectroscopy is an efficient method for obtaining quantitative data on the fractional ¹³C enrichment of metabolic intermediates or end-products. In biosynthetically directed fractional ¹³C labelling using uniformly ¹³C labelled carbon source, the biomass becomes ¹³C labelled in a metabolic flux distribution dependent manner and the cleavage and...

To examine bonding nature of fluorine ligands in a metal coordinated system, ¹⁹F high-resolution solid-state NMR has been applied to TiF₄, which bears both bridging and terminal fluorines. By referring to the calculated isotropic shifts using DFT, the observed 12 isotropic signals were assigned to 12 crystallographically different fluorines (6 terminal (F_T) and...

The fundamental importance of protein-glycan recognition calls for specific and sensitive high-resolution methods for detailed analysis. Binding of small molecules to proteins is often monitored by observing ¹H NMR resonances of the ligands due to the inherent high sensitivity of ¹H detection. Ligand-observed schemes may, however, fail, because of spectral overlap, if...

Cyanobacteriochromes (CBCRs), proteins responsible for detection of light in cyanobacteria, are special not only because of their comparatively simple architecture, but also because they show an astonishing broad spectral variability. Like structurally related canonical phytochromes CBCRs use bilin molecules to absorb the light, but instead of the PAS-GAF-PHY tridomain which is necessary in...

Metabolic syndrome (MetS) is a cluster of metabolic abnormalities that generate an increased risk in the onset of cardiovascular disease (CVD), liver disease, type 2 diabetes and chronic kidney disease. According to the World Health Organization (WHO), MetS is defined as the presence of insulin resistance and other two of the following risk factors: obesity (waist circumference or BMI ˃ 30...

The large diversity of nucleic acid structures can be expanded even further by the introduction of metal-mediated base pairs in which base pairs are generated by coordination to metal ions instead or in addition to hydrogen bonds.[1,2] These metal-mediated base pairs consist of either natural or artificial nucleobases and are frequently used for the programmable and site-specific insertion of...

Phytochromes sense red/far-red light and control many biological processes in plants, fungi, and bacteria. Using crystallography, information about the two meta-stable states Pr and Pfr, has been gained. This series of discrete structural changes is believed to be responsible for phytochrome intracellular signaling. However, the structural characteristics of these meta-stable states remains to...

Direct interaction between intrinsically disordered proteins is often difficult to be characterized hampering the elucidation of their binding mechanism. Particularly challenging are the cases of extreme fuzziness of the complex, which is now appearing as a common interaction mode,requiring new models for their description.¹
So far, nuclear magnetic resonance spectroscopy has...

2D J-resolved NMR spectroscopy, separating chemical shifts and J couplings along two independent dimensions, serves as a promising tool for studying molecular structures and compositions. In practice, the classic homo-nuclear 2D J-resolved spectroscopy [1], generally suffers from phase-twist lineshape and field inhomogeneity effects, thus rendering its potential applications limited. Here, a...

NMR spectroscopy is a nondestructive characterization technique that provides detailed information on molecular structures with incomparable specificity. With NMR, it is possible to observe chemical reactions, detect chemical substances, and to determine concentrations.

Commercial NMR devices are usually bulky, expensive and power hungry. To change this situation, our approach uses integrated...

Recently, the function of proteins is much more attract attention and measurement of high-pressure NMR about proteins showed many remarkable results in this field. We reported zero-field splitting (ZFS) parameter D term was increased depending on load pressure raise that used the hemin as a model compound of metalloprotein using ESR employing terahertz light and high–pressure (HP–THz ESR). On...

A signature trait of NMR spectroscopy is its limited sensitivity due to low, field-dependent polarisation across spin states. Several hyperpolarisation methods have been developed to overcome this barrier, however, such techniques typically require expensive and complex instrumentation. The introduction of Parahydrogen (p-H₂) based methodologies, however, provide pathways for...

Dissolution dynamic nuclear polarization (D-DNP) is currently the subject of many new developments in view of boosting the sensitivity of nuclear magnetic resonance spectroscopy (NMR) and imaging (MRI). Most D-DNP probes are designed for one or two nuclei at most. The investigation of multiple nuclei, therefore, requires manufacturing a number of different costly probes. In addition, changing...

Electron-nuclear double resonance (ENDOR) spectroscopy is the method of choice for detecting magnetic nuclei in biomolecules which contain an unpaired electron spin is. However, due to its low gyromagnetic ratio, the detection of deuterium couplings is a particular challenge for ENDOR spectroscopy. The standard Mims ENDOR sequence, generally used for small couplings, suffers from line shape...

α1-adrenoceptors (α1-ARs) comprise three G protein-coupled receptor (GPCRs) subtypes that stimulate smooth muscle contraction in response to binding adrenaline and noradrenaline. α1A-AR and α1B-AR are clinically targeted for treating hypertension and benign prostatic hyperplasia but are putative drug targets for neurodegenerative diseases. New subtype-selective tool compounds are required to...

Fitting a weighted sum of exponentials to a noisy exponential decay is an ill-posed problem. In the T₂ relaxation context, it leads to non-unique solutions because different sets of relaxation times and amplitudes give identical least-square distance between the model and the experimental data. Conventional data analysis combine a non-negative least squares (NNLS) algorithm...

In modern organic and medicinal chemistry, fluorine is commonly used to enhance the chemical properties of molecules in many desirable ways: it may delay the metabolism of the molecule, reduce the toxicity of aromatic groups, or increase the bioavailability. As a result, it is estimated that more than 20% of commercial pharmaceutical APIs and 30% of agrochemicals contain at least one fluorine...

The hyperpolarization of biologically relevant molecules for signal-enhanced magnetic resonance detection holds great promise for studying biological processes in vitro and in vivo. Being important metabolites as well as the building blocks of peptides, the canonical amino acids are promising targets for hyperpolarization, and a number of parahydrogen based strategies have been...

Abstract: We present the design of a portable one-sided low cost system for EPR applications that uses a new shimming approach to achieve the required homogeneity. The proposed permanent magnet offers an open geometry enabling non-destructive EPR measurements on arbitrarily large objects. It has been designed, simulated and optimized using the finite element method. The system is based on...

NMR spectra provides indispensable information such as chemical shift and scalar coupling which plays a pivotal role in molecular structure determination and analysis. Unfortunately, it is often difficult to extract proton-proton scalar coupling since signals are often hidden in overcrowded regions in conventional 1D NMR spectroscopy.
Hence, the gradient-encoded selective refocusing method...

NaK and other non-selective channels are able to conduct both sodium (Na⁺) and potassium (K⁺) with equally high efficiency. In contrast to previous crystallographic results, we show that the selectivity filter (SF) of NaK in native-like lipid membranes adopts two distinct conformations that are stabilized by either Na⁺ or K⁺ ions. The atomic...

There exists a number of experimental methods which provide homodecoupled (pure-shift) 1H NMR spectra. Standard techniques (like PSYCHE [2] and TSE-PSYCHE [3]) require to record spectra in a pseudo-2D mode where chunks of data are acquired as separate FIDs. However, this often leads to very time-consuming experiments [1]. The problem with time rises, when a series of pure-shift proton spectra...

Pure-shift NMR [1] is a branch of techniques allowing the suppression of homonuclear J-couplings in an NMR spectrum. This gives a boost in resolution as multiplets in a spectrum collapse into singlets. The techniques rely on echo-type pulse sequences with selective pulses. In between the pulses, a short chunk of an FID is acquired. The whole FID is then constructed from these chunks.
The type...

The combination of a phase-modulated (PM) saturation pulse and symmetry-based dipolar recoupling into a rotational-echo saturation-pulse double-resonance (RESPDOR) sequence has been employed to measure ¹H-¹⁴N distances. Such a measurement is challenging owing to the quadrupolar interaction of ¹⁴N nucleus and the intense ¹H-¹H homonuclear...

Magic‐angle spinning (MAS) is an essential ingredient in a wide variety of solid‐state NMR experiments. The standard procedures to adjust the rotor angle are not highly accurate, resulting in a slight misadjustment of the rotor from the magic angle (~54.74°) on the order of a few millidegrees. This small missetting has no significant impact on the overall spectral resolution, but is sufficient...

Accurately determined conformations of biological agents are valuable assets in drug discovery. By enabling rational modifications, knowledge of the conformational envelope of biological ligands may enable the design of increased binding affinity, reduced off-target effects, or the discovery of an entirely new chemical series through “scaffold hopping”. The use of NMR to study the range of...

Unambiguous characterization of different acid sites in zeolites is of great importance in heterogeneous catalysis. In addition to various well-characterized extra-framework Al species, tri-coordinated framework aluminum species can also serve as Lewis acid site (LAS) in zeolites, which is however “NMR-invisible” due to its extremely distorted/asymmetrical local environment resulting in the...

The zeolites are well known for the decades for their excellent properties as adsorbents and catalysts. The large-scale application of these materials is ensured by petroleum chemistry as a part of fuel cracking catalysts (FCC) for gasoline production and hydrockacking catalysts (HCK) for diesel due to their thermal stability, strong acidity, and developed specific surface area. A main...

Conventional methods for determining crosslink densities (CLDs) in elastomers, such as equilibrium swelling of vulcanizates (using the Flory-Rehner equation), and stress-strain measurements (using the Mooney-Rivlin equation) lack phase-specific distinction of crosslink densities in elastomer blends [1]. NMR spectroscopy offers better solutions to overcome these limitations, but studies...

The aggregation of beta-amyloid peptides is closely associated with Alzheimer's disease. We have used different chemical devices such as liposomes and reverse micelles to encapsulate the 40-residue beta-amyloid peptides so that the spatial confinement could lead to the formation of nonfibrillar aggregates of beta-amyloid peptides. These on-pathway beta-sheet intermediates were used to seed the...

The general problem of NMR and MRI is their low sensitivity. The NMR/MRI signal intensity is proportional to the nuclear spin polarization that is on the order of 10⁻⁵ or less at a common magnetic field of NMR/MRI. On the other hand, triplet dynamic nuclear polarization (triplet-DNP), a method to enhance NMR/MRI sensitivity using photoexcited triplet electrons, has the great...

The protein family of small GTPases controls cellular processes by acting as a binary switch between an active and an inactive state. The most prominent family members are H Ras, N Ras, and K Ras isoforms, which are highly related and frequently mutated in cancer. Bisphenols are widespread in modern life because of their industrial application as plasticisers. Bisphenol A (BPA) is the best...

Phase-alternating decoupling (XiX) [1,2] is one of the simplest and efficient high-power decoupling methods in solid-state NMR for faster MAS frequencies. It consists of two pulses of equal length but with a phase difference of 180°. We present variations of this heteronuclear decoupling sequences with improved performance based on numerical calculations of the second-order cross terms [3]. By...

The amyloid fold is a generic fold characterized by highly repetitive stacking of β-strands into fibrillar polymers. Amyloids are involved in various pathologies but also display different adaptive functional roles in animals, fungi and bacteria. Numerous proteins can adopt the amyloid fold, pointing to its adaptability to high sequence variability; yet amyloid propensity is also highly...

Abnormal protein aggregation is a common hallmark of Alzheimer’s disease and other neurodegenerative disorders. Despite the growing interest in their pathogenesis, no existing method can capture aggregate nucleation and subsequent growth at atomic resolution in real time. In this study, we have recently established high-sensitivity Rheo-NMR spectroscopy that enables us to detect atomic-level...

This article is committed to developing a portable method for accurate detection of human blood glucose by low field nuclear magnetic resonance technology. A portable NMR apparatus (magnetic field frequency: 26 MHz) was constructed by manufacturing a miniature NMR probe for micro sample detection and integrated with a lightweight permanent magnet and an electronic control system.
In order to...

Recently the phenomenon of Liquid-Liquid Phase Separation (LLPS) has gained great interest among the scientific community given its participation in the formation of membraneless organelles that play crucial roles in the cellular environment 1. Great efforts are currently devoted to its structural and functional characterization. However, obtaining structural information at the molecular level...

We introduce an efficient, yet easy to use, homonuclear dipolar recoupling scheme by employing a chirp pulse or a train of chirp pulses. It operates well at any MAS spinning rates, but is especially superior to other methods known to dates at an ultrahigh MAS spinning rate (νr = 60 kHz). This method is useful for generating cross peaks between any sites that possess small, medium, or large...

Liquid state (Overhauser) Dynamic Nuclear Polarization (DNP) experiments have been performed at high magnetic fields (9.4 T) on aqueous solution of ¹⁴N-TEMPOL nitroxide radicals. To determine the saturation factor of the electron spin, the ¹H paramagnetic shift as a function of the microwave power was measured as previously reported ^[1]. We could show that the...

Intrinsically disordered proteins (IDPs) are abundant in eukaryotic proteomes and act at the heart of fundamental cellular processes such as cell cycle control and signal transduction. The aberrant function of IDPs is therefore associated with severe diseases such as cancers and neurodegenerative diseases. Protein functions are mediated via motions, therefore a detailed characterization of...

Tc toxins are 1.7 MDa protein complexes that are found in insect- and human-pathogenic bacteria. After endocytosis, Tc penetrates the membrane of the host’s cells and translocates a deadly enzyme into the cytosol. The complex consists of three subunits: the 1.4 MDa TcA pentamer, which mediates target cell association, membrane insertion and toxin translocation, and two smaller subunits, TcB...

The inversion of NMR relaxation time is very important to study object’s molecular dynamics. The inversion is to solve the Fredholm integral equation of the first kind with non-negative constraints, which is known as an ill-posed problem. In this paper, a novel method is presented for NMR inversion based on the regularization method. The proposed objective function can transform the...

The ability to select the signal passing through chosen coherence pathways is a powerful feature of NMR. Nuclear singlet states are coherent states that have effective spin 0[1]. Singlet states can be used to sustain hyperpolarized signal [2], to study slow dynamic phenomena[3] and to filter signal originating from specific spin ½ pairs[4,5].
Despite being NMR silent, singlet states can be...

Motivation

Among other factors, the sensitivity of Magnetic Resonance Imaging (MRI) is limited by the low polarization of the sample investigated. Enhancing the polarization offers several orders of magnitude in signal enhancement. In comparison to e.g. Dynamic Nuclear Polarization (DNP), para-hydrogen (pH₂) based approaches are less cost intensive, scale well and offer high...

Recently, widespread N6-methyladenosine (m6A) modification of messenger RNA (mRNA) and non-coding RNA was discovered in yeast, flies, mammals and plants [1]. At the functional level m6A plays an important role in many biological processes [2]. In mammals two methyltransferases: METTL3 and METTL14, together with the adaptor protein WTAP are required for m6A methylation [3]. In plants MTA and...

Selective anion binding to a catalytic host is a promising topic on the route to develop systems triggering catalytic activity. In this regard, cooperative hydrogen bonding by multiple 1,2,3-triazoles establishes a suitable environment for different anions. On this basis, the asymmetric dearomatization of quinolines was successfully introduced by anion binding catalysis [1]. However, the...

Oxidative stability of oils is an important quality issue especially during deep-fat frying process. It is well known that lipid oxidation can lead to changes in functional, sensory, and nutritive values and even the safety of fried foods. Extracts of many plants have been reported to have varying degrees of antioxidant activities, which increase the oxidative stability of fats and oils....

Multiple-quantum MAS (MQMAS) NMR spectroscopy is one of the most widely used techniques in solid-state NMR for gaining site-specific resolution of overlapping central-transition lineshapes for half-integer quadrupolar nuclei.[1,2] However, a major drawback of this method is the low MQ excitation and reconversion efficiency, which has led to broad variety of MQMAS sequences with improved...

Proteins in biological environments exist as part of crowded mixtures. Biopharmaceutical proteins for injections also often have to be formulated at very high concentrations (100-400 mg/mL) and as mixtures. Characterizing protein self-interactions vs cross-interactions in such complex systems in situ is challenging, but is required for adequate system description.

Recently our group and...

Deuterium ($^2$H) NMR is well-suited for probing the structure and dynamics of materials. The study of $^2$H via NMR has gained popularity owing to the abundance of hydrogen in materials and the ease to substitute with $^2$H and most importantly due to favorable NMR properties of $^2$H. $^2$H has spin $I = 1$, and has a quadrupole moment, the interaction of which with the electric-field...

Pulmonary compliance is an important index for evaluating the function of the lung, which could reflect the pulmonary ability to stretch and expand. Hyperpolarized ¹²⁹Xe MR is a powerful tool in quantifying the microstructure and function of the lung in vivo, and it has unique advantages in measuring the gas volume in the lung. In this study, a proof-of-concept method was proposed...

Calculation of NMR parameters helps in the prediction, assignment and analysis of spectra. We present the application of the recently developed methodology for combined DFT and ab initio computation of paramagnetic shifts [1-4] to a series of 7 paramagnetic systems [Ln(III) with Ln = Pr, Nd, Sm, Eu, Er, Tm, Yb] with 1,10-phenanthroline and diethyldithiocarbamate ligands (1:3 ratio). Theory and...

The restrictive limits of molecular tumbling have made the study of large proteins and protein complexes a subject ideally suited to the strengths of magic-angle-spinning (MAS) solid-state NMR. Protons form a dense network of strong dipolar interactions and their shifts are sensitive reporters of protein structure and interactions. Higher MAS rates and highly deuterated samples have allowed...

Inorganic materials and compounds with transition metals find numerous applications within catalysis, environmental remediation as well as for energy storage and conversion due to their flexible oxidation states. However, their characterization is challenging due to the absence of long-range order, structural defects and/or the multi-phase nature of such materials. Solid state NMR (SSNMR) is...

The development of improved heterogeneous catalysts can be undertaken in a rational way by a better understanding of their atomic-level structures. Solid-state NMR spectroscopy is very well suited to the study of heterogeneous catalysts because it can give information on the local structure. However, the lack of sensitivity and resolution limits the characterization of surface sites, notably...

Ubiquitination and proteasome-dependent degradation of proteins is a major regulatory mechanism of protein function in eukaryotic cells^[1]. The covalent attachment of ubiquitin to substrates occurs through the recruitment of three enzymes: a ubiquitin-activating enzyme E1, an E2 ubiquitin-conjugating enzyme and an E3 ubiquitin ligase. The E2 and E3 enzymes are the key components in...

Petroleum derived asphaltenes are known to be the most complex fraction of crude oil. They are also known to be coke precursors in refinery process resulting in several problems such as catalyst deactivation and poisoning because of their tendency to flocculate and precipitate during oil upgrading process. It is needed to understand more thoroughly the structures and behaviors of asphaltenes...

Benchtop NMR spectrometers are a promising tool for chemical laboratories worldwide because of their moderate price and low handling cost. The easy setup of flow measurements makes them convenient to use for reaction/process monitoring. However, their applications are mainly limited to simple tasks. This is due to the insufficient spectral resolution and sensitivity, which are a consequence of...

The protein P2 is a member of the class of FABPs (Fatty Acid Binding Proteins). Its function in the organism is totransport fatty acids (FAs) out of the intercellular system and bring them to the myelin sheath around axons in the PNS (peripheral nervous system).
A reversible neuronal disease known as “Charcot-Marie-Thooth disease” leads to a reversible myelindegeneration and one theory...

Block copolymers (BCP) due to their unique self-assembling properties represent important group among synthetic materials and they are believed to play significant role in future nanolithography. It appears that below certain critical temperature TODT (order-disorder transition temperature) two dissimilar subchains (blocks) become immiscible and tend to separate one from another gathering with...

Relaxation dispersion techniques are powerful tools to quantitatively characterize the chemical (or conformational) exchange across biologically relevant timescales [Palmer et al, Meth. Enzymol. 2001 & 2019]. Recently, a new type of data analysis, geometric approximation methodology [Chao & Byrd, JACS 2016], has been developed to decipher the complex experimental data associated with the...

We have recently shown that the hyperpolarized material obtained by dynamic nuclear polarization (DNP) at cryogenic temperatures can be transferred from the polarizer magnet to a target magnet in the solid form while maintaining a high level of the nuclear spin polarization - this method is named bullet-DNP [1]. This approach allows for rapid sample transfer and minimal dilution of the...

In Bullet-Dynamic Nuclear Polarization the sample is transferred from the polarizer to the target magnet as a solid. In the target magnet it is rapidly dissolved – transfer and dissolution take approximately $900\ \mathrm{ms}$. As we have previously reported we can achieve liquid-state $^{13}$C polarization levels of $30\%$ at less than 10-fold dilution while using sub-mL solvent volumes as...

UFM1 is an ubiquitin like protein (UBL), which shares high structural but little sequence similarities to ubiquitin. Like ubiquitin it can be covalently attached to target proteins by specific enzymatic cascade called ufmylation. Ufmylation of target proteins plays a role in central cellular events, such as gene transcription, response to cell stress and differentiation. The process of...

The current theoretical model for predicting the NMR chemical shifts of paramagnetic systems is based on a modern version of the Kurland-McGarvey theory, and relies of the computation of EPR parameters (hyperfine couplings, zero-field splitting and g-tensor) with quantum-chemical methods. While the zero-field splitting and g-tensor can be calculated ab initio with sufficient accuracy using...

A broad range of compounds utilises carbon nitride sheets C3N4 (CN), which consist of heptazine units. This structural analogue of graphene sheets appears to manifest semiconducting properties with ~2.7eV energy gap, which allows photochemical reactions in direct sunlight. Other advantages include chemical and thermal stability and non-toxicity - advantages of CN open new applications in the...

Incredible Natural Abundance DoublE QUAntum Transfer Experiment (INADEQUATE) is arguably one of the most attractive tools for establishing molecular structure. When applied to organic molecules it usually relies on J coupled ¹³C spin pairs. While this results in a spectrum that is easy to interpret, it also comes at a cost of very low sensitivity considering that only ca. 0.01% of...

RIP2 is an intracellular adaptor protein that is essential for several reaction cascades. RIP2 is recruited when the bacterial fragments activate the innate immune pattern recognition receptors NOD2 and NOD1. That leads to NF-κB associated activation of proinflammatory cytokine production. Also, RIP2 involved in signal transduction by transmembrane neurotrophin receptor P75. That pathway is...

The high relevance of G protein-coupled receptors (GPCRs) becomes apparent from their diverse distribution in human tissue and their participation in a variety of physiological functions. This makes them highly interesting molecules for basic research and also a major target for pharmaceutical drugs.
Besides the structural architecture of the seven transmembrane proteins and its interaction...

Cell migration is of prime importance for physiological processes like immune response, tissue repair, and embryonic morphogenesis [1]. Essential for the attachment and migration of cells across surfaces is the formation of focal adhesions [2, 3]. The cell surface receptor family of the integrins plays a key role as linker proteins between intracellular and extracellular environments. The...

Uropathogenic Escherichia coli invades and colonizes hosts by attaching to cells using adhesive pili on the bacterial surface. Although many biophysical techniques have been used to study the structure and mechanical properties of pili, many important details are still unknown. Here we use proton-detected solid-state NMR experiments to investigate solvent accessibility and structural...

To decorate biotechnologically prepared proteins with chemically synthesized polymers opens the route to hybrid molecules and materials with novel and unique properties.
The protein component may provide highly specific biochemical activity whereas the polymer part may improve long-term stability, modulate bioavailability and enable the integration of biological function into bulk...

The Wnt signaling pathway is a crucial regulator of bone development in vertebrates. Through its activation, bone mass and mineral density is increased. A negative regulator of this pathway is the protein sclerostin. By binding the LRP5/6 co-receptor of the canonical Wnt pathway, sclerostin suppresses the binding of the Wnt ligand and consequently the bone growth and remodeling. In the...

RNA is a versatile biomolecule that plays an important role in many cellular processes e.g. translating the genetic information, gene regulation, and reaction catalysis in organisms. NMR spectroscopy can be used to obtain conclusive informations about the structure and dynamics of a system, as well as to investigate interactions of RNA with proteins, ions or ligands. However, long RNAs with...

Cholera is an acute, diarrheal illness caused by infection of the intestine by the bacterium Vibrio cholerae. An estimated 2.9 million cases and 95,000 deaths occur each year around the world. During infection, the bacterium releases a toxin. The cholera toxin is an oligomeric complex made up of six protein subunits: one copy of the enzymatic A subunit and five copies of the receptor binding B...

Channelrhodopsin-2 (ChR2) is a light-gated ion channel[1] which over the last years has attracted considerable interest due to its unparalleled role in optogenetic applications[2]. However, despite considerable efforts, it has remained elusive how molecular events during the photocycle including the retinal trans-cis isomerization and the de/re-protonation of the Schiff base are coupled to the...

Cleavage of DNA is a vital process in all living systems. Such process is involved in replication, transcription and other cellular transactions, where the leading role belongs to enzymes and specific cofactors. In general, three different types of DNA cleavage can be distinguished, namely i) DNA hydrolysis, ii) photochemical cleavage and iii) oxidative cleavage, although the last two...

Recently, the proposal and concept development of using chip-integrated voltage-controlled oscillator for electron spin detection has gained significant attention in the research community. Being at the same time highly sensitive and compact in size, these ESR-on-a-chip detectors are ideally suited for next generation portable ESR spectrometer [1]. Moreover, thanks to the fast electronic...

Parkinson’s disease and several other neurodegenerative diseases are accompanied by the misfolding and aggregation of the natively monomeric protein α-synuclein. Many disease-related mutants of α-synuclein have modified N-terminals which will impact their interaction with membranes, while oligomers have been shown to cause membrane permeabilization which can potentially disrupt cell...

Gating modifier toxins (GMTs) from spider venoms may serve as pharmacological hits for treatment of hereditary diseases caused by mutations in genes coding voltage-gated sodium channels (Nav). Nav channels are transmembrane proteins, consisting of one pore domain and four surrounding voltage-sensing domains (VSDs). In particular, mutations in the S4 transmembrane helical segments of the VSDs...

Acylgermanes are efficient germanium-based photoinitiators (PIs) that are suitable for medical applications such as dental fillings.^[1–4] Remarkably, this class of compounds displays electron-transfer properties being comparable with phosphorus-based photoinitiators.^[5]

Here we present a combined EPR/DFT/CV approach to characterize the redox properties of acylgermanes....

Nuclear magnetic resonance (NMR) spectroscopy is a very powerful tool of investigation in structural biology, providing structural and dynamic information at atomic resolution on a protein either alone or in its interaction with small molecules or with other proteins/nucleic acids [1-2].
Electron Paramagnetic Resonance (EPR) spectroscopy well complements NMR data providing information useful...

Intramembrane proteases catalyse the hydrolysis of their substrates within the hydrophobic environment of the lipid bilayer and are involved in several diseases and the functional activation of substrates [1]. SPPL proteases belong to the class of GxGD aspartyl proteases. It is still unknown how members of this family distinguish between substrates and non-substrates, or which factors...

The nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-κB) protein family comprises transcription factors that play an important role during human immune response. The family encompasses homodimers and heterodimers of five component proteins that mediate various transcriptional responses. These proteins are structurally very similar, suggesting these dimeric complexes may...

The vast volume of sea oil transport and rise in the number of underwater drilling platforms all around a world creates a great risk for environment. To minimize the ecological impact of possible water spills there is a need for cheap, oil selective materials used for cleaning oil spills from the sea surface.

In the recent years a new branch of aerogel material made up of cellulose...

The bioactivities and physical-chemical properties of chitosan are strongly dependent on the contents of 2-acetamido-2-deoxy-D-glucopyranose (GlcNAc) and 2-amino-2-deoxy-D-glucopyranose (GlcN) units, which define the average degree of acetylation (DA). In this study, high molecular weight chitosans with variable DA grades (5 to 60%) were produced by multistep ultrasound-assisted deacetylation...

Riboswitches are functional RNAs acting as cis regulatory genetic elements. The binding of a specific ligand at the aptamer domain stabilizes a certain conformation or causes conformational changes that influence the gene expression. One of these riboswitches is represented by the guanidine-II riboswitch (mini-ykkC) [1]. It consists of two conserved stem-loops P1 and P2 connected via a linker...

Riboswitches are RNA structures that regulate the downstream gene expression upon binding of a small molecule ligand. The guanidine-II riboswitch is a guanidine-binding translational ON switch that is present in many proteobacterial species. The associated genes are usually involved in guanidine detoxification. This riboswitch class is characterized by two hairpins (P1 and P2) with an ACGR...

The Two-Partner Secretion (TPS) pathway in Gram-negative bacteria is dedicated to the export of large proteins serving notably as virulence factors. TpsB transporters are transmembrane β-barrel proteins secreting their TpsA substrates across the outer membrane. They belong to the ubiquitous Omp85 superfamily mediating protein insertion into or translocation across membranes. In the whooping...

Intrinsically disordered proteins (IDPs) are polypeptides lacking a well-defined structure under biologically native conditions. As a result, they are best described as an ensemble of fast-exchanging conformations. The flexible nature of IDPs allows them to adopt distinct ensembles upon binding to different partners and to carry out multiple biological functions. One such protein is...

Aromatic side chains are attractive probes of protein dynamics on the millisecond timescale, because they are often key residues in enzyme active sites and protein binding sites. Furthermore, they allow to study specific processes, like histidine tautomerization and ring flips. Here we investigate the possibility of aromatic ¹H CPMG relaxation dispersion experiments as a...

2D NMR spectroscopy is an extremely useful method for analyzing the structure and dynamics of small molecules in liquids and in solid state. Modern 2D NMR approaches allow obtaining direct information about the geometrical configuration of small molecules, which is very important when solving problems of modern physical chemistry of fluids (e.g. micronization of drug substances,...

Several human diseases result from malfunctions of ABC systems. Many ABC exporters contain asymmetric nucleotide-binding sites (NBSs) and some of them are inhibited by the transported substrate.[1] To actively transport diverse chemically substrates across biological membranes, ATP-binding cassette (ABC) transport complexes use the energy of ATP binding and subsequent hydrolysis. In this work,...

Riboswitches are RNA elements that are involved in the regulation of genes. They bind small metabolites and undergo upon metabolite binding conformational changes that switches the corresponding genes on or off. The Guanidine-II Riboswitch binds guanidine and is composed out-off two stem loops, P1 and P2, connected via a single strand. X-ray crystallography on the isolated P1 and P2 stem...

Conventional nuclear magnetic resonance (NMR) experiments are limited by low sensitivity. Hyperpolarization techniques such as dynamic nuclear polarization (DNP) enhance NMR signals by several orders of magnitude [Larsen et. al. 2003]. Most dissolution-DNP (dDNP) applications involve the use of weakly magnetic isotopes such as ¹³C, but excessively long...

Conjugated organic molecules exhibit unique optical, magnetic and electrochemical properties, and have been used for organic molecular magnets and organic thin-film devices such as solar cells, organic light emitting diodes (OLED), or organic field effect transistors. Their properties are strongly affected by the spin structures, which can be effectively investigated by Electron Spin Resonance...

Introduction
Neuroendocrine prostate cancer (NEPC) is a subtype that arises as the tumor develops resistance to androgen deprivation therapy (ADT). Preliminary data has displayed the ability of hyperpolarized (HP) 13C pyruvate MRI to detect high-grade PC and provide early evidence of metabolic response to therapy1,2. The goal of this study was to develop a serum marker to measure the...

The dangling bond (db) is the most prominent electronic defect in hydrogenated amorphous silicon (a-Si:H). Acting as recombination centers for charge carriers, dbs crucially determine the electronic material properties. Understanding the mechanism of db-related recombination thus constitutes one of the most fundamental issues concerning a-Si:H.
Since a neutral db is paramagnetic, the ideal...

Overcoming noise in experimental signals has been an age-old problem in magnetic resonance. Apart from improving instrument sensitivity, data processing approaches such as model fitting and signal filtering have been applied with limited success. Current data processing methods focus on capturing the signal from the noisy data, which often requires a priori information and may be limited to a...

Some quantum computation schemes rely on having ordered structures of qubits with nano-scale positioning accuracy to perform correctly. One natural candidate for such a system of qubits is an ordered structure of electron spins in a solid-state sample. Such systems (e.g. $\text{NV}^{-}$ centers in diamond, and phosphorus doped $^{28}\text{Si}$) exist in unordered forms, and have been shown to...

Delta subunit of RNA polymerase is exclusively present in Gram positive bacteria. It was proven that it is important for virulence of the bacteria, it ensures the quick and proper response to the changing cell environment conditions, and its role for regulation of RNA polymerase activity was also demonstrated [1]. However, the function of the delta subunit is not fully understood at molecular...

A wide ensemble of protein-protein interaction networks warrants communication and information exchange between cells. These interactions are mainly mediated by protein domains, which could be considered as protein modular building blocks assembled in different fashions. They decode specific signals emerging from post-translational modifications involved in receptor signaling, endocytosis or...

Hyperpolarization by dissolution dynamic nuclear polarization [1] has emerged in the last decade as a powerful tool for boosting the sensitivity of magnetic resonance by orders of magnitude. This has for instance brought metabolic imaging to reality [2]. Unfortunately, hyperpolarization’s lifetimes in all molecules hardly exceed a minute. This means that hyperpolarization needs to be produced...

Paramagnetic restraints have been used in Biomolecular NMR for the last three decades in order to elucidate and refine structures but also to characterize protein/ligand interactions¹. Pseudo Contact Shifts (PCS) are the most commonly used restraints, consisting in measuring a shift between a paramagnetic species and a diamagnetic reference, whose magnitude depends on the distance...

Recently the access to ¹⁹F-containing screening libraries has started a great pharmaceutical interest for ¹⁹F-based screening methods. Especially the ¹⁹F-CPMG experiment can be used for detection of protein-ligand interactions. However, when screening large libraries of fluorinated organic compounds, pulses that cover the ¹⁹F-bandwidths of 120 kHz on...

Site-directed spin labeling (SDSL) is a powerful technique to monitor highly dynamical conformational states of membrane proteins in both NMR and EPR. In this work, the nitroxide spin label MTSL was introduced to single cysteines in the G protein coupled neuropeptide Y2 receptor (Y2R) that has been associated with a number of key physiological functions, including the regulation of appetite...

The relationship of pancreatic cancer (PC) and diabetes mellitus (DM) is obvious, as more than 2/3^rd of the cancer cases are diagnosed with DM. This so-called pancreatogenic diabetes (T3cDM) appears prior to PC within a period of three years and is accompanied by characteristic features such as absence of obesity or frequent infections¹. PC belongs to the most lethal...

Intrinsically disordered proteins (IDPs) are enriched in “disorder-promoting” residues such as proline. In solution Xaa-Pro bonds can undergo a cis-trans isomerization. Functional studies show the biological relevance of the different types of conformation.1 The cis-isomer is less frequent (5-15 %) due to steric hindrances and effects also the proline surrounding residues....

Ferredoxins (Fdxs) are soluble iron-sulfur proteins that function as electron acceptors and donors in diverse metabolic pathways. They are characterized by their acidity and low redox potentials ( 230 to 420 mV). The unicellular green alga Chlamydomonas reinhardtii contains 12 different plant-type [2Fe2S]-Fdx isoforms.$^1$ The most abundant isoform Fdx1 has been characterized extensively...

Solid-state dynamic nuclear polarization (DNP) NMR utilizes radical-bearing polarization agents to enhance the signal of nearby nuclei. Consequently, small sample sizes along with insensitive and higher-dimension experiments become feasible on realistic time scales. These sensitivity gains are particularly intriguing for applications to biological systems, where the molecule of interest is...

The pulsed dipolar EPR spectroscopy (PDS) techniques such as double electron-electron resonance (DEER) or relaxation-induced dipolar modulation enhancement (RIDME) detect the magnetic dipolar interaction within pairs of paramagnetic species from which the spin–spin distances and distance distributions can be extracted. By combination with site-directed spin labeling (SDSL) PDS became a...

The electrolytic reduction of carbon dioxide (CO₂) is a promising option for the future of sustainable energy as chemical energy storage. Specifically, the electrolysis of CO₂ in aqueous media using silver electrodes yields carbon monoxide (CO), which can be used to produce CO₂-neutral fuels via Fischer-Tropsch synthesis. The technical implementation of this...

Heteronuclear-detected NMR experiments are becoming increasingly more common due to the constant development in cryogenic probes. These experiments are particularly beneficial with respect to nucleic acids due to the inherent low proton-density and limited ¹H-chemical shift dispersion. Here, we present ¹⁵N- and ¹³C-detected NMR experiments that enable...

We have been developing a millimeter (mm)-wave ESR/NMR double magnetic resonance system in ultra-low temperature and high magnetic field regions aiming for direct detection of diluted nuclear spins.
Increase of nuclear magnetization by using dynamic nuclear polarization (DNP) may enable direct observation of NMR.
One of our targets is a silicon crystal doped lightly with phosphorus...

Fast field cycling (FFC) NMR relaxometry enhanced by DNP [1] has recently been reported to obtain T₁ relaxation time dispersion with increased sensitivity and selectivity to study molecular dynamics in various systems. First studies were devoted to the measurement of the DNP spectrum and enhancement as well as DNP-enhanced dispersion curves of polymer systems in the presence of...

Cyclosporin A, well known as an immunosuppressive agent, is one of a family of congeners synthesised in certain soil fungi. Three natural variants of cyclosporin (B, C, D) were studied by high resolution NMR spectroscopy in chloroform and dimethyl formamide. CsB has alanine in position 2 instead of $\alpha$-aminobutyric acid (Abu2) found in CsA, in CsC this residue is replaced by threonine,...

G-quadruplexes are DNA secondary structures containing stacked guanine tetrads stabilized by central cations. They are formed by self-assembly of guanine-rich oligonucleotides by Hoogsteen base pairing. Studies have shown that G-quadruplexes form in vivo in oncogene regulatory regions and at telomeric ends of chromosomes, thus shortening cancer cell lifetimes [1].

Many G-quadruplex species...

Type II collagen is the most abundant macromolecule in articular cartilage. In the tissue collagen forms anisotropic, fibrillous structures. Longitudinal relaxation is generally thought to be isotropic in articular cartilage [1]. We investigate the conditions needed to observe the anisotropy of the collagen network in the longitudinal relaxation time $T_1$.

We have computed longitudinal...

With a staggering energy density of 142 MJ kg$^{-1}$, three times larger than that of petroleum, hydrogen became one of the most valuable and environmentally-friendly fuels [1]. Hydrogen is an energy carrier that does not suffer from energy dissipation (electricity as a direct energy source does), since the energy is chemically stored; however, it lacks of adequate means of confinement and...

Within the last 15 years dynamic nuclear polarization (DNP) has emerged as an efficient tool to boost the sensitivity of various magnetic resonance techniques[1]. Dissolution DNP has proven its applicability in magnetic resonance imaging (MRI) as well as solid-state DNP in nuclear magnetic resonance (NMR)[1]. However, liquid state NMR DNP is still in its infancy. Even though the general...

We apply solid-state MAS NMR-spectroscopy at different temperatures to investigate protein folding and misfolding on a molecular level [1].
On the one hand, we exploit DNP-enhanced MAS NMR spectroscopy at low temperatures (~100K) to investigate conformational ensembles of intrinsically disordered proteins IDPs). Such proteins are not represented by a single well-defined structure but rather by...

The ability of corals to maintain homeostasis and mineralize has been compromised by ocean acidification and temperature rise causing reefs to recede and even vanish. Therefore, corals have been serving lately as important proxies of environmental impact on marine life. As newborn, corals undergo transformation from a swimming organism (planula) to an benthic immobile one (polyp), that lives...

Enhancement of NMR signals using dynamic nuclear polarization (DNP) enables studying systems that are difficult to tackle with conventional NMR due to low concentrations or low overall quantities of material. One particular example is amyloid-beta peptide, which self-assembly in human brain tissue leads to neurodegeneration in Alzheimer’s disease (AD). Previously, various intermediates along...

Proteorhodopsin (PR) is found in marine bacteria in various ecosystems and is one of the most abundant photoreceptors. It converts light into a transmembrane, electrochemical gradient and forms functionally unresolved higher oligomers. Although the PR monomer is able to undergo a full photocycle, the question arises whether the pentameric complex formed in the membrane via specific...

Proton detection under fast magic-angle spinning has been enabling spectroscopists to overcome their hurdles and involve innovative routes to access various information sought for solid proteins. We could develop tools that would grant access to proteins of increasing complexity in the last years, ranging from assignments over structure and dynamics to protein interactions.1,2 In particular,...

The purpose of the present work to investigate the dosimetric properties of various asthma drugs using Electron Paramagnetic Resonance (EPR) Spectroscopy. Since asthma drugs are widely used, it would be valuable to determine dosimetric properties to be used as emergency dosimetry. For this purpose, pulverized asthma tablets were irradiated with 60Co gamma source at a dose range of 10-1100 Gy...

Accurate geometrical tracking of the tip of a catheter during minimal invasive surgery using intervention MRI provides a surgeon with orientation relative to the body. The tip can be visualized in the MR environment by locating a micro-resonator at this position. If the resonator is tuned to the Larmor frequency of abundant nuclei, and subject to a radio frequency excitation pulse, it's motion...

The Proliferating Cell Nuclear Antigen-associated factor p15PAF (hereafter named p15) is a 12 kDa nuclear protein that regulates DNA repair during DNA replication (1). The p15 gene is overexpressed in several types of human cancer and its function is regulated by double monoubiquitination at lysines K15 and K24. Upon UV stress p15 is degraded facilitating the recruitment of the trans-lesion...

Dynamic nuclear polarization (DNP) has proved to be a powerful and versatile means to overcome the intrinsically low sensitivity of NMR[1]. A great challenge for DNP at present is to achieve high spin polarization in shorter times, which requires understanding spin polarization transfers but also spin diffusion dynamics[2].
Spin diffusion is indeed of major importance nearby the free...

Based on the process of ionic self-assembly (ISA) we characterize the formation of loosely bound ion-based colloid-like globular clusters of several nanometer size, termed globular ionoids.[1-2] Here, our model system contains the 'Texas-sized molecular box', developed by Sessler and coworkers[3] as a mechanically interlocked molecule to create elegant noncovalent architectures (e.g. molecular...

β-lactamases pose a great threat to our healthcare system, yet may simultaneously present potential solutions. We used CEST, CPMG relaxation dispersion and T₁, T₂, NOE Lipari-Szabo analyses to characterise the dynamic behaviour of the β-lactamase of Mycobacterium tuberculosis, BlaC, over a wide range of timescales. BlaC is mostly rigid on the fast timescales and shows...

We investigate the dynamics of CO2 adsorbed in a metal-organic framework (MOF) in high pressure range (~1 MPa) utilizing the combination of MAS NMR and CSA analyses. MAS NMR spectra show adsorbed CO2 adsorbed and free mobile gas-phase CO2. Analyses for the dynamics by T1 measurement suggest that the adsorbed CO2 in pores has very slow mobility corresponding to the values reported for some...

The activities of membrane proteins strongly depend on their dynamics; herein we made use of proton-detected MAS at very high-field and of relaxation violated experiments in liquid state NMR to describe the dynamics of the membrane domain of the Outer Membrane Protein A of Klebsiella pneumoniae (KpOmpA) in liposomes and in micelles.
From ¹⁵N relaxation rates and...

The cells are subjected to a precise control of survival, growth, differentiation, and apoptosis. During the process of cell proliferation it is also subject to errors which may lead to loss of cell growth control, initiating the growth above the necessity of the tissue which can cause tumors. One of the pathways that undergoes changes is the Mitogen Activated Protein Kinases (MAPK), which is...

The 117-residue GABA_A receptor-associated protein (GABARAP) from H. sapiens is a versatile key regulator in autophagy. GABARAP is found as a soluble protein in the cytosol, as well as anchored to autophagosomal membranes during autophagosome formation and maturation. Anchoring to phospholipid membranes is achieved via enzymatic C-terminal lipid-conjugation of GABARAP, but the...

We consider the behaviour of precessional phase carried by molecules of a diffusing specimen under magnetic fields typical of magnetic resonance experiments. A time evolution equation for the ensemble of particles is constructed, which treats the phase as well as the position of the molecules as random variables. We refer to the associated probability density function $p ({\vec x}, \phi |t)$...

Oncogenic variants of kras gene are among the most important mutations causing cancer. KRas protein is a membrane-bound small GTPase which acts as a molecular switch and plays a key role in many signal transduction pathways regulating cell proliferation, differentiation, and survival. It alternates between its GTP-bound active and the GDP-bound inactive conformers. The most frequent oncogenic...

Polyethylene terephthalate (PET) is one of the most widely used plastics worldwide and is applied, i.a., as packaging material in the food industry.^[1] Like many polymers, PET is susceptible to photochemical degradation and absorbs in the ultraviolet (UV) range.^[2]
As already known, UV irradiation of PET leads to shorter molecular chains and thus to a higher number of...

Purpose: 4D flow magnetic resonance imaging (MRI) allows to measure and visualize blood flow in vivo . This is in particular interesting for the investigation of the effect of flow diverter stents used for treating aneurysms. However, metallic stents induce artifacts on MRI like other metal objects. It was realized before that the effect of these artifacts on the measured flow is important but...

Dynamic Nuclear Polarization (DNP) is the most widespread and ubiquitous technique for signal enhancement in Nuclear Magnetic Resonance (NMR). Introduction of the ability to arbitrary modulate the 193 GHz waveform used for excitation of the electron spins at 7 Tesla resulted in up to a factor of 4 improvement in DNP efficiency under varying range of experimental conditions and across different...

G-quadruplexes are structurally diverse non-canonical secondary structures formed by guanine-rich nucleic acids capable of performing a broad range of cellular functions, most notably regulation of gene expression. As independent aptamer molecules, G-quadruplexes can also bind specific cytosol or extracellular proteins, which makes them promising drug targets for treatment of various diseases....

So far, we investigated the electronic structure of novel type of organic conductors, ammonium tetrathiafulvalene carboxylate (TTFCOO) and its and tetrathiapentalene derivative (TTPCOO) by high-field ESR and NMR measurements. The pristine TTFCOOH and TTPCOOH molecules are closed-shell. Kobayashi and coworkers (NIMS, Japan) found that self-doped type carrier was generated by substitution of the...

Collagens are the most abundant components of the extracellular matrix (ECM). Due to their diverse structures and compositions, collagens serve many functions, providing structural and mechanical support for surrounding cells, and playing important roles in cell-to-cell communication. Nonetheless, despite being at first glance a simple protein formed by three homologous polypeptide chains of...

We have demonstrated that ¹H spin–spin relaxation time (T₂), which is measured by using low field NMR techniques, is an effective parameter to elucidate the degradation behavior of poly (urea-urethane). It is difficult to reveal the degradation behavior of poly (urea-urethane), when the degradation proceeds in urea or urethane bond units.
We prepared two types of poly...

Results of CIDNP studies of a series of rigidly linked electron donor/electron acceptor dyads (D-X-A) are presented consisting of triarylamine (TAA) and naphthalene diimide (NDI) moieties with spacers X. After photoexcitation charge separation occurs, where the TAA unit serves as electron donor and the NDI unit as the acceptor. Variation of the magnetic field allowed us to obtain a pronounced...

Pyrrolo[1,2-a]benzimidazole and pyrrolo[1,2-a]quinoxaline skeletons are present in various bioactive compounds. Thus, pyrrolo[1,2-a]benzimidazole scaffold is present in a range of DNA cross-linkers mimicking the mitomycin antitumor activity against a range of human cell lines, and many pyrrolo[1,2-a]benzimidazole derivatives showed beneficial properties on central nervous system...

β-peptides are important peptidomimetic compounds. Here the formation of ordered backbone conformation of new pentamer β-peptides was studied by NMR (¹H, ROESY, TOCSY, COSY NMR techniques) and ECD spectroscopy. The investigated pentamers include trans-[R,R]-2-aminocyclohexanecarboxylic acid (trans-[R,R]-ACHC) building blocks interrupted by different elements in the middle of...

Currently, proton nuclear magnetic resonance (1H-NMR) have been combined with electrochemistry (EC) to observe reaction pathways and identify products generated due to its high selectivity, capacity in chemical structure determination [1], and quantitation [2]. We have utilized NMR in our electro-catalysis researches, with a representative example that electro-catalytic performances of...

Nuclear magnetic resonance (NMR) spectroscopy serves as a versatile analytical tool. Resolution is an essential challenge in NMR spectroscopy. Due to the limited range of chemical shifts and extensive signal splittings due to scalar couplings, signal congestion and even overlap are common in NMR spectra, especially in the widely used proton spectra. One major approach to enhance spectral...

The present reports the results of the experimental study of static and dynamical characteristics of the Er3+ ions in the YGa3(BO3)4 crystals. g-factors and the constants of hyperfine interaction are found. The ratio gzAx/ gx*Az is close to unity that is an evidence of insignificant admixing of the excited multiplets. The widening of the absorption lines related to the temperature increase...

Amino acid radicals are involved in essential processes in primary metabolism such as photosynthesis, respiration, and biosynthesis of DNA building blocks. They serve as one-electron redox cofactors in biocatalysis and multistep proton-coupled electron transfer (PCET) reactions. E. coli class Ia ribonucleotide reductase (RNR), which catalyzes the reduction of nucleotides to their...

Hsp90 is a central chaperone performing its activity hydrolyzing ATP with Mg(II) as cofactor. Hsp90 is homo-dimeric and each monomer consists of 3 domains (CTD, MD, NTD). The ATPase site is in the NTDs, while the CTDs are dimerized. In absence of nucleotide Hsp90 is in ‘open’ conformation shifting to an ATP-bound ‘closed’ conformation by dimerization of the NTDs.[1] Yet, there are still open...

Hybrid perovskite frameworks are an emerging family of materials with interesting dielectric, ferroelectric and magnetic properties which are useful in such applications as charge storage and optoelectronic devices. These porous frameworks are composed of metallic centers joined together by organic linkers. Each such pore confines a single molecular cation. The majority of such frameworks...

Proteins are increasingly being used in numerous technological applications such as biosensors, biofuel cells and biocatalysts. Often the immobilization of a protein in a synthetic matrix is essential.^1,2 Porous matrices have warranted much attention due numerous factors, such as their high surface areas, meaning improved protein loading and high number of active sites; the...

Dense metal-formate frameworks of general formula [A][M(HCOO)₃]_n attracted significant attention of the scientific community due to the indications of the multiferroic behavior [1]. These compounds consist of transition metal ions (M²⁺) linked by formate groups into porous frameworks, where each pore confines a single molecular cation (Aⁿ⁺). The...

Almost invariably, the information content of the NMR spectrum, both in terms of structure and dynamics, increases with improved spectral resolution. For this reason, most biomolecular applications have been based on carbon detection since proton signals were too broad, principally due to proton-proton dipolar coupling. Through technical developments in faster magic-angle spinning, the line...

Conventional diagnostic magnetic resonance imaging (MRI) techniques have focused on the improvement of the spatial resolution by using high magnetic fields (1-7T). High field allows the visualization of small tumour mass but lacks to give a precise evaluation of tumour grading and metastatic potential. Recently,[1,2] we showed that the intracellular water lifetime represents a hallmark of...

RNA does not only translate the genetic code into proteins, but also carries out important cellular functions. Understanding such functions requires knowledge of the structure and dynamics at atomic resolution. Almost half of the published RNA structures have been solved by NMR, but as a result of severe resonance overlap and low proton density, high-resolution RNA structures are rarely...

The rapid methodology development of sensitivity-enhanced SSNMR spectroscopy has been empowering its success in a broad range of challenging fields in life science. Here I will present a new methyl SSNMR toolkit for exploring the protein structures that offers new types of NMR parameters for decoding the complex molecular systems. These approaches meld DNP-enhancement, heteronuclear NOE, tamed...

Ubiquitination is a post-translational modification of proteins that is mainly involved in signalling the labelled protein for degradation. The E1-E2-E3 cascade is responsible for attaching a ubiquitin molecule to the target protein in the following process. First the E1 activating enzyme attaches one ubiquitin molecule to the E2 ubiquitin conjugating enzyme, and then with the help of E3...

A complete description of the pathways and mechanisms of protein folding requires a detailed structural and energetic characterization of the folding energy landscape. Simulations, when corroborated by experimental data yielding global information on the folding process, can provide this level of insight. Molecular Dynamics (MD) has often been combined with force spectroscopy experiments to...

Brevinin-1BYa (FLPILASLAAKFGPKLFCLVTKKC) is a 24-amino acid residue host-defence peptide, first isolated from the skin secretions of the foothill yellow-legged frog Rana boylii. The peptide is of interest as it shows broad-spectrum antimicrobial activity, and is particularly effective against opportunistic yeast pathogens. Its potential for clinical use, however, is hindered by its latent...

Arkadia is a RING E3 ubiquitin ligase that positively regulates TGF-β signaling pathway by mediating degradation of the negative regulators Smad6 and Smad7 and the nuclear co-repressors Ski and Skil (SnoN)1,2. The domains that are required for the substrate recognition and ubiquitin ligase activity are located in the highly conserved area of the C-terminal 100 amino acids. This region is...

We propose an easy and precise method of quantitation by NMR, using the neat protonated solvent as external concentration reference. Spectra of the analyte in a deuterated solvent, e.g. chloroform-d, and the neat solvent, in this case protonated chloroform, are taken in the same conditions, i.e. the same relaxation delay, pulse width, acquisition time and receiver gain. The linearity of the...

Because of the hyperfine coupling between unpaired electrons and nuclear spins, NMR signals in paramagnetic systems often experience large shifts and possess short relaxation times, particularly in close proximity to the metal center, rendering observation of active sites in metalloproteins particularly challenging.
Here, we illustrate how, by adapting a set of NMR experiments originally...

The modern era chemistry laboratory curriculum combines pedagogically rich experiments with modern analysis techniques, such as MS and NMR. While 1-dimensional NMR has long been used, 2D techniques are not yet standard as they are more complex and usually time-consuming. But these modern experiments allow for unambiguous assignments of resonances and resolution of overlapped regions in more...

NMR spectroscopy has proven a valuable tool in differentiation of the geographical origin of various food products.^[1] The geographical origin is influenced by the composition of metabolites due to different exogenous factors such as soil, temperature or water availability. The concept of a metabolomics-based approach based on the determination of a molecular fingerprint which is...

NMR spectroscopy provides detailed insight into molecular structures and is capable of quantitation without standards. An area of interest for chemical industry is the possibility to use NMR to rapidly analyze wastewater streams with anomalously high TOC (Total Organic Carbon). A high TOC excursion can lead to regulatory violations and the consequent danger of shutting down an entire...

A fragment screen using ligand detected 19F NMR versus a kinase target will be described. In addition, practicalities of sample preparation and mixture design will be discussed. Furthermore, a TopSpin/Perl script package for automatic analysis of 19F NMR based screening data will be presented.

Among the translated proteins are few validated drug targets. A recent estimate, based on currently approved drug substances, listed 218 validated protein targets. The choice of non-coding RNA as a drug target could be an alternative approach to efficiently control biomolecular signaling pathways. Currently, clinical trials are underway with oligonucleotides and small molecule drug candidates...

Iron(III) porphyrins play vital roles as catalysts, protein cofactors, and single-molecule magnets (SMMs). SMMs represent potential candidates for spin-based nanoscopic data storage due to slow relaxation of the magnetization below their blocking temperature. Since the zero-field splitting (ZFS) parameters D and E strongly affect the properties of intermediate- and high-spin ferric...

Toxin-antitoxin (TA) systems are essential for bacterial persistence under stressful conditions. In particular, M. tuberculosis express VapBC TA genes that encode the stable VapC toxin and the labile VapB antitoxin. Under normal conditions, these proteins interact to form a non-toxic TA complex, but the toxin is activated by release from the antitoxin in response to unfavorable conditions....

Guanine-rich DNA oligonucleotides can adopt non-canonical, four-stranded secondary structures, termed G-quadruplexes. The formation of G-quadruplexes requires the presence of cations. In fact, cation nature is one of the major factors contributing to the structural diversity of G-quadruplexes. Their self-assembling ability, electrochemical properties and programmable control of their shape and...

The undisputed usefulness in biomedical applications, the high carbon polarization (up to 70%) and the long relaxation time constant after dissolution have made neat [1-¹³C]pyruvic acid (PA) plus trityl the most studied dissolution DNP sample.
Therefore, sometimes the literature is lacking detailed studies for different trityl-based samples, limiting the potential of other...

Fifteen years after its invention, dissolution dynamic nuclear polarization (dDNP)[1] has become one method of choice to enhance signals in both MRI and liquid state NMR. Despite exciting prospects, this method remains restricted to few research groups as it needs in principle to be performed at the point of use, with specialized equipment and personnel. However, a series of recent advances...

Hyperpolarization via dissolution DNP (dDNP) is a highly promising technique that has advanced into a powerful modality for non-invasive real time monitoring of normal and abnormal cellular physiology with the potential to unravel diseases, develop novel treatment regimes, and quantify enzymatic processes. ^{1, 2} An important enzyme in this context is branched chain amino acid...

Geopolymers are inorganic polymers, mainly based on minerals of geological origin (see e.g. ref. [1]). Their acid resistance, as well as low CO₂ footprint, make it an attractive construction chemical.

Geopolymerization is a multi-step reaction, typically conducted in alkaline media. It involves dissolution of a precursor, re-organization & condensation, and hardening, on a time...

Rapid-scan (RS) electron-spin resonance (ESR) is a technique to boost the signal-to-noise ratio (SNR) in ESR experiments by allowing the use of larger B1 magnitudes without saturating the sample. State-of-the-art rapid-scan setups [1] use fast field sweeps produced by modulation coils in combination with relatively low-Q resonators to achieve a large detection bandwidth. Due to effects of the...

Understanding the physico-chemical basics of protein-membrane interactions are of key importance in functional characterization of the cell membrane. In order to simplify this complex system the best membrane mimetics are bicelles, which at q=0.5 (long chain/short chain lipid) ratio are ideal for solution state NMR studies^1,2.
We chose biologically relevant protein fragments: the...

The importance of glycans in life and disease has been demonstrated during the past few years. Indeed, it is today a hot topic with diverse branches and perspectives. The field is therefore attracting increased attention and it is expected that will provide spectacular developments. Herein we describe the application of NMR methods to unravel fine structural details of molecular recognition...

Ionic liquids (ILs) and Deep Eutectic Solvents (DESs) are two strongly related classes of materials of great interest in green chemistry and with enormous potential in several technological and industrial applications.
ILs are well-known low melting salts with unique physicochemical features. To tune properties and structural organization of the final materials, there is nowadays a growing...

South Africa’s coastline, stretching more than 2500 km from the cold temperate coast west coast to the warm tropical environment of northern Kwazulu-Natal, has an exceptional environment with a high percentage of endemic species. SA’s rich marine biodiversity therefore signifies the production of potent, biologically active, natural products (Davies-Coleman & Beukes, 2004). By 1995, 60% of the...

The Heme group is synthetized in a biosynthetic pathway by 8 enzymes. Defects on these enzymes lead to a family of diseases called Porphyria. To understand the consequences of the alteration of this route, it is important to gain knowledge about its regulation and the changes in its metabolites. The development of a mathematical model of the route will provide us the capacity of predicting the...

Dynamic Nuclear Polarization (DNP) is an emerging magnetic resonance technique to enhance the sensitivity of MAS NMR. In a typical MAS DNP experiment, several mechanisms are involved simultaneously when transferring the relatively large polarization of paramagnetic electrons to NMR active nuclei of interest. Recently SCREAM-DNP (Specific Cross Relaxation Enhancement by Active Motions under...

Techniques of high-frequency electron paramagnetic resonance (EPR) and electron spin echo (ESE) were applied for investigation of non-Kramers Tb³⁺ centers in single crystals of yttrium aluminum garnet, Y₃Al₅O₁₂ (YAG). The EPR-ESE techniques were created on the base of highly stable microwave bridges, quasiresonant system for supplying microwave power...

Huntigton’s disease (HD) is an incurable neurological disorder triggered by the aberrant expansion of the polyglutamine tract present in the huntingtin protein (HTT). The pathological version of HTT (with more than 35 consecutive glutamines) is prone to aggregate and form insoluble fibrils within neurons, affecting their normal functions. However, the precise mechanism by which the expanded...

The alarming rise of drug-resistant bacteria urgently calls for novel antibiotics. A particularly interesting class of antibiotics target essential Lipid II molecules that are present in bacterial membranes, killing even the most refractory bacteria at nanomolecular concentrations. Unfortunately, the native binding modes of these membrane-active antibiotics are unknown due to the enormous...

The structural investigation of the C-terminally farnesylated peroxisomal protein PEX19 was complicated by the fact that isotopically labeled apo PEX19 had to be enzymatically farnesylated in vitro with farnesyl pyrophosphate. Since this reagent is only available in natural abundance, the reaction will inevitably lead to an isotopically unlabeled farnesyl moiety, while the protein moiety...

Among the various alternative DNA structures, G-quadruplexes exhibit a remarkable variety of topologies. In this study, two adjacent guanosine residues adopting syn glycosidic bond conformations in a G-quadruplex of (3+1)-hybrid type were substituted by anti-favoring 2’-F-riboguanosine nucleosides (FrG). Residue-specific ¹⁵N labeling along with 2D NOE,...

Geological disposal of high-level radioactive waste usually includes bentonite buffer materials. However, the long-term performance of the bentonites for the containment of the nuclear waste is being increasingly questioned due to specific issues associated with “homogenisation” occurring in these materials. Homogenisation is driven by erosion, variations in density and development of swelling...

Lithium is a leading drug for the treatment of bipolar disorder and affects many biochemical pathways via inhibition of phosphatases and kinases. Lithium can replace magnesium cations in enzymes and small molecules, among them ATP. Yet, despite its fundamental pharmaceutical importance, the mode of binding of lithium to ATP has never been directly observed. Here we present the binding...

The Proliferating cell nuclear antigen (PCNA) is a ring-shaped DNA sliding clamp (~90 kDa homo-trimer) that acts as a processivity factor of replicative DNA polymerases. PCNA is a very promiscuous protein and recognized to interact with many proteins via what is known as PCNA Interaction Protein sequence (PIP-Box). The human (h) PCNA and its yeast (sc) variant hold 35% sequence identity and...

Telomeric regions are found at ends of chromosomes and protect the chromosome termini from deterioration or from fusion with neighbouring chromosomes. Due to their high G content, repetitive sequences in telomeres are able to fold into short four-stranded structures called G-quadruplexes. Telomere attrition is closely associated with cell aging and exposure to reactive oxygen species (ROS)....

Hyperpolarization techniques have the potential to improve the sensitivity of magnetic resonance imaging (MRI) by more than four orders of magnitude.1 Various hyperpolarization techniques have been used to generate hyperpolarized contrast agents to study and diagnose diseases in vivo.2 Amongst the challenges of designing hyperpolarized contrast agents, two are persistent: the need to create...

Hyperpolarized ¹²⁹ Xenon NMR spectroscopy provides a powerful method to investigate porous materials as has been shown on silica-based materials of MCM-41 structure in previous work in our group [1]. It offers insights to pore sizes, pore geometries and diffusivity. We are planning to apply hyperpolarized Xenon NMR for probing surface-functionalized porous materials based on...

Magnetic Resonance Imaging (MRI) was proven to be a powerful tool for studying catalytic reactions in operando due to its non-invasive nature and versatility. However, MRI application for gas-phase reactions studies is particularly challenging because of low spin density of reactants and products, and it’s further hampered by inhomogeneity of the magnetic field, associated with the presence...

It has been demonstrated that hyperpolarization using PHIP can be effectively achieved using a ruthenium-based trans-hydrogenation catalyst in contrast to typical cis-hydrogenation reaction [1,2]. This led to a development towards hyperpolarized metabolites such as fumarate, using pairwise trans-hydrogenation of an unsaturated precursor [3]. Aside of the desired reaction to form...

Hyperpolarization techniques are used to enhance NMR signals by several orders of magnitudes. Para-Hydrogen Induced Polarization (PHIP) is a practical and cost-effective method with great potential for medical applications. Moreover, the hyperpolarization of biocompatible solvents has potential for versatile applications in structural biology and medical imaging. Our group recently...

Hyperpolarisation provides the means to dramatically increase the signal-to-noise ratio in an NMR spectrum, however, the useful lifetime of the hyperpolarized state is limited by relaxation processes that lead to the re-establishment of thermal equilibrium over time. In order to make hyperpolarisation useful for experiments requiring lengthy delays for magnetisation transfer, chemical exchange...

Studying intrinsically disordered proteins (IDPs) under physiological conditions may present a great challenge using methods based on H_N detection. The main drawback is the signal loss caused by chemical exchange of amide protons with water. Thus, conventional triple-resonance methods such as HNCA, HNCACB and HNCO fail to provide satisfactory information. The alternative way of...

With the recent record power conversion efficiency of 17.3% ^[1], organic solar cells have become serious contenders among third generation photovoltaics. This success is related amongst other things to efforts in overcoming the drawbacks of organic semiconductors, such as their low exciton-dissociation yield and charge-carrier mobility, as they limit device performance.
Studying...

Proteins of the MAP1 (microtubule-associated protein) family are implicated in the regulation of microtubule spatial organisation and stability. One of its members is MAP1B, a predominantly neuronal protein required for neuronal network formation and synaptic maturation in murine brain development. ^[1],[2] Its importance is further highlighted by its implication in several human...

Abelson tyrosine kinase (Abl) is an ubiquitously expressed kinase associated with a number of cellular signaling processes. The regulatory core of Abl consists sequentially of the N-cap, the SH3 and SH2 domains, and the kinase domain (KD) N- and C-lobes. The N-Cap differs between two splice variants, 1a and 1b. Abl 1b is 19 residues longer and N-terminally myristoylated. Under physiological...

In the food industry, low-field NMR has become the standard for solid fat content (SFC) determination of edible fats. The T₂-relaxation behaviour of a semi-solid sample distinguishes a fast and slow relaxing part after a 90°-pulse, hence an FID experiment, related to the solid fat and liquid oil, respectively. Yet, data acquisition only starts after the 90°-pulse and the dead time....

DEER on orthogonally spin labeled proteins [1] is a versatile technique that allows to retrieve a much greater information content from a single sample than DEER on proteins spin labeled with just single type of label. The reason behind is that orthogonal spin labels can be addressed independently in DEER experiments due to spectroscopically non-overlapping central transitions and/or distinct...

In recent years Dynamic Nuclear Polarization (DNP), a hyperpolarization technique that boosts the NMR sensitivity, has become a powerful tool for structural studies. DNP applications span from the solid-state NMR studies of proteins, to the development of heterogeneous catalysts. However, its use has been mainly limited to low magnetic fields, due to the unfavourable field dependence of the...

Tumour associated macrophages (TAMs) are forced by the cancer cells to adopt an anti-inflammatory phenotype and secrete factors to promote angiogenesis and tumor invasion [1]. For these reasons, sensitive and non invasive methods to detect TAMs are needed for tumour classification and individual patient stratification to stronger or targeted therapies.
Herein we propose a new, alternative...

Microstructure and texture evolution of foods during cooking is difficult to characterize, because conventional techniques cannot analyze the internal structure, while preserving product’s integrity. For apple, one of the most processed fruits, understanding thermal degradations in essential. Such phenomena was thus approached with in-situ quantitative NMR during the cooking process.

Five...

¹H-detected solid-state NMR experiments with fast magic-angle-spinning (MAS) frequencies deliver ¹H chemical shifts of proteins in solids, which enables their interpretation in terms of secondary structure. We present ¹H and ¹³C-detected NMR spectra of the RNA polymerase¹ subunit Rpo7 in complex with unlabeled Rpo4 and use the...

DNA - the most important intercellular target for UV radiation - can be damaged through the direct absorption by nucleobases, or through photosensitized reactions with endogenous cellular chromophores. Guanine that has the lowest oxidation potential among all DNA components is the main target of one-electron oxidation reactions. Guanine radicals are supposed to be involved in the formation of...

Quantitative magnetic resonance imaging (qMRI) has become one of the hotspots in the field of clinical diagnosis and scientific research. qMRI can be used for direct comparison of results across subjects and sites because it removes some confounding effects, such as experimental conditions, RF coils, equipment setups and so on. However, traditional qMRI usually takes long acquisition time and...

The prion protein (PrP) is responsible for several neuropathies belonged to Transmissible spongiform encephalopathies (TSE). The TSE connected with changes of the PrP structure from nontoxic cellular (PrPC) to protease resisted (PrPSc) forms. The transition from PrPC to PrPSc provide to formation fibrils contained β-strands conformation. The cellular form of the PrP protein demonstrated two...

Biofilm formation is a common feature of bacterial colonies enabling them to gain an advantage in environments with high evolutionary pressure. Our research focuses on biofilms of the bacterium Baccillus subtilis at the air-liquid interface of standing solutions. The long–term aim is to acquire basic insights on a molecular level through application of solid-state Nuclear Magnetic Resonance...

We here analysed using solid-state NMR different conformational states of the ATP-Binding Cassette (ABC) transporter BmrA reconstituted in lipids by spectral fingerprinting.
ABC transporters convert the energy gained from ATP hydrolysis to make a trans-bilayer movement of substrate. ABC transporters are present in all kingdoms of life, and notably those which transport a large variety of...

Efficient and controlled molecular doping of organic semiconductors promises to significantly advance the field of organic electronic devices. However, an in-depth understanding of the doping process is required to guide the design of improved semiconductor materials and molecular dopants.$^1$ Electron Paramagnetic Resonance (EPR) Spectroscopy is uniquely suited to investigate the nature and...

Hydrothermal carbon (HTC) materials derived from biomass are of considerable current interest due to low cost, environmentally desirable properties, and a broad range of potential applications, for example as functional materials, catalysts, absorber, or electrode material. Especially nitrogen-doped carbon materials are now playing an important role in energy conversion and storage...

In Nuclear Magnetic Resonance (NMR), magnetic field dependent phenomena attract considerable interest: Paramagnetic relaxation enhancement (PRE) is theoretically, experimentally and from the application point of view an important research area, always looking for new relaxation agents with specific properties especially at high magnetic fields and for improved understanding of the PRE...

1H-detected fast magic-angle-spinning (MAS) solid-state NMR is emerging as an important analysis method for proteins of which only sub-milligram amounts are available. This makes also integral membrane proteins which can be expressed at low yields only accessible for a structural investigation by solid-state NMR.
On the example of the Hepatitis C viral membrane protein NS4B (Non-Structural...

Understanding the function of a protein requires not only knowledge of its tertiary structure but also an understanding of its conformational dynamics. Nuclear magnetic resonance (NMR) spectroscopy, polarization-resolved fluorescence spectroscopy and molecular dynamics (MD) simulations are powerful methods to provide detailed insight into protein dynamics on multiple timescales by monitoring...

Both prion protein (PrP) and amyloid beta (Aβ) play important roles in the pathogenesis of neurodegenerative disorders as they are able to misfold and form toxic assemblies. Aβ oligomers have been identified as neurotoxic agents relevant for the pathogenesis of Alzheimer's disease. Recently, it was shown that human PrP (hPrP) is a receptor for oligomeric Aβ(1-42)^1,2. We previously...

The Na⁺-translocating NADH:quinone oxidoreductase (Na⁺-NQR) is a large protein complex found in V. cholerae. It is a part of the respiratory chain involved in energy metabolism and Na⁺-homeostasis. The Na⁺-NQR consists of six structurally heterogeneous subunits (NqrA-F) and at least six redox-active cofactors coupling the free energy liberated during...

Human DNA helicases, BLM (Bloom syndrome protein) and FANCJ (Fanconi Anemia Group J) have a common interaction partner, Replication Protein A (RPA). It has been identified that the interaction of BLM and FANCJ with RPA stimulate their DNA unwinding ability, but binding properties of both proteins to RPA were not investigated. Here, we present interactions of RPA-BLM and RPA-FANCJ by NMR...

α-Synuclein (AS) is an amyloid protein involved in Parkinson’s disease. In pathological cases, it aggregates in the dopaminergic neuronal network, leading to a progressive degeneration accompanied with a dramatic decrease in dopamine levels. Under physiological conditions, AS is disordered in solution or weakly bound to neuronal membranes, via the formation of α-helices. The triggers and steps...

Edema factor (EF) is a major virulence factor of Bacillus anthracis, the bacteria that causes of anthrax. After activation by intracellular calmodulin (CaM), EF catalyzes the production of supraphysiological levels of cyclic AMP (cAMP), thus interfering with several host essential intracellular processes. The activation by CaM induces the folding of a disordered switch in EF that results in...

Bacterial second messengers regulate a wide range of cellular functions from biofilm formation to growth and survival. Targeting second messenger networks is challenging because the system involves a multitude of components with often overlapping functions. Here, we present a novel strategy to intercept cyclic diguanylate (c-di-GMP) signaling pathways by directly targeting the second...

J-proteins are a large and very diverse class of indispensable chaperones that are mainly known as co-chaperones for the ATP-dependent chaperone Hsp70. Only together with J-proteins, Hsp70 can carry out such different functions as protein folding, prevention of protein aggregation and the facilitation of protein degradation (1). The task of J-proteins is to deliver client proteins to Hsp70 and...

The confinement of materials in nanoporous media greatly affects their thermal and dynamic properties such as melting point, glass transition temperatures etc. Size of the pores and the host-guest interaction at the interfaces play an import role in the confinement effect. Here, we study the effect of the confinement, in particular, surface chemistry on the interfacial structure and the...

Multidimensional NMR is a central tool in many fields but suffers from long experimental durations limiting its use for many applications such as reaction monitoring or high-throughput metabolomics. The duration of 2D NMR experiments can be reduced to less than a second with the "ultrafast" 2D NMR approach introduced in 2002 by Frydman et al. This technique makes it possible to acquire 2D...

Slowly relaxing molecular motions, from nanoseconds up, strongly affect molecular properties, even modifying their chemical functions. Nuclear magnetic relaxation (NMR) data is sensitive to these time-scales and therefore its interpretation provides information on the structural and dynamics characteristics of molecules.
Simple approaches allow extracting information easily for rigid molecules...

Metabolomics is the study of all metabolites in biological samples. These small molecules constitute a unique chemical fingerprint of the metabolic status, and are insightful markers for many diseases. Not only metabolites play important roles in their free forms, but also they bind to macromolecules to carry out their functions in signaling, regulation and other cellular processes....

If the intracerebral hemorrhage (ICH) rehabilitation animal models studies have included processes related to imaging diagnosis, not only interim evaluation of treatment effects, but also objectification of treatment effects would have been possible. The purpose of this study was to examine the rehabilitate treatment effect bio-marker by Magnetic resonance imaging/spectroscopy in animal intra...

Using Methyl-TROSY HMQC based experiments in selectively labelled proteins is an important strategy for studying large and dynamic systems$^{[1]}$. A key issue faced is the chemical shift assignment of the methyl resonances in proteins where experiments that link side-chains to the backbone are unfeasible. Recent structure-based chemical shift assignment methods obtain the methyl assignment...

Since the original discovery of amlodipine, the 2-substituted 1,4-dihydropyridines have attracted considerable attention due to their various biological activities [1]. For the aimed synthesis of novel therapeutic agents, it is important to establish what structural factors influence their biological activity. For this purpose the original synthetic method was elaborated and the modification...

Cross-β fibrils (aka amyloid fibrils) are a hallmark of many neurodegenerative diseases. Every mechanism of potential cross-β fibril toxicity will have to be mediated by the (abnormal) interaction of the fibril surface with cellular binding partners. We are studying the firbril surface in the context of huntingtin exon-1 (HTTex1) important in Huntington’s Disease (HD). The core of HTTex1...

Pseudocontact shift (PCS) NMR is a powerful technique to study interactions, dynamics and structures of proteins, protein – protein and protein – ligand complexes in solution. Trivalent lanthanide ions are the most useful class of paramagnetic centres for PCS NMR and allow to determine the position of nuclei over distances larger than 80 Å from the metal. Lanthanide chelating tags (LCTs) have...

Over the last decade, the use of periodic density functional theory (DFT) calculations to aid the assignment and interpretation of NMR spectra of complex solids has become almost mainstream. This new link between bulk crystallographic structure and local NMR interactions via the electron density has given birth to the field of NMR crystallography.
Here, we investigate the NMR crystallography...

Dynamic nuclear polarization (DNP) provides a significant sensitivity gain for solid-state NMR under magic-angle spinning (MAS). However, both resolution and selectivity are of high importance as well, and may be compromised under DNP conditions. Particularly, this applies towards biomolecular applications where inhomogeneous line broadening under cryogenic conditions often prevents...

Lanthanide-doped yttrium aluminum garnet (YAG) is a widely used class of materials in solid-state lasers as well as other optical applications. The analysis of the dilute substituent species requires powerful state of the art experimental techniques that focus on the local structures and how they interact with the YAG host lattice [1]. 27Al solid-state Nuclear Magnetic Resonance (NMR) is a...

Although metabolomics has been widely applied to study metabolic changes in various diseases including autoimmune diseases, it is still very limited used? in autoimmune skin diseases. Our study is focused on pemphigus vulgaris (PV) which is a life-threatening autoimmune skin disease resulting from intercellular dissociation in the epidermis. By using a keratinocyte cell model of PV which...

A large ribonucleoprotein complex called the ribosome is responsible for several steps of protein synthesis in all organisms. In bacteria, regulation of translation begins at initiation. Despite the availability of structural information, we still lack a clear understanding of how the ribosome encounters folded mRNA structures during translation initiation.
A general mechanism for initiation...

Metalloenzymes catalyze a broad range of chemical reactions. Their catalytic activities and compatibility with different reaction conditions depend on the detailed electronic properties of the metal active site and seemingly small modifications may cause significant changes in catalytic properties. Recently, we exploited this fine-tuning of enzymatic catalysis by incorporating a non-canonical...

RNA helicases are enzymes that unwind double stranded RNA in an ATP dependent reaction. They have shown to be important players in RNA metabolism in both eukaryotes and prokaryotes. RhlB is a DEAD-Box RNA helicase from E.coli. It constitutes an essential part of the RNA catabolizing enzyme complex degradosome. Its ATP dependent unwinding reaction, which features a strong bend in the RNA, is...

Dengue is the most widely spread mosquito-borne viral disease affecting the human population. It is estimated that about 390-million dengue infection occur each year, of which 96 million shown signs of severity. Dengue virus (DENV) is a single-stranded positive-sense RNA virus featuring an icosahedral, ordered envelope and a nucleocapsid of unknown structure.

The structure of the Dengue...

The aberrant folding of certain proteins results in toxic oligomers and aggregates involved in a plethora of diseases. Alzheimer’s disease, the most prevalent debilitating and fatal neurodegenerative disorder is linked to misfolding of the protein amyloid beta. Pathological indicators which confirm AD include brain shrinkage, plaques and neurofibrillary tangles, whereby the plaques are mainly...

The hepatitis C virus (HCV) causes acute and chronic hepatitis with approximately 70 million infected people worldwide. HCV life cycle in infected cells is functionally linked to membrane structures and lipid metabolism. Transmembrane protein NS4B is one of major contributors to formation of membranous replication organelles and thus playing a crucial role in viral genome replication and...

In our studies, we are focusing on the E. coli rRNA methyltranserfases RlmJ and RlmF that
methylate the exocyclic amino group of adenine 2030 and adenine 1618 in 23S rRNA during the
early stages of ribosome assembly, respectively. In the case of RlmJ, the substrate secondary
structure consists of an 18-nucleotide-long hairpin loop that is methylated using S-(5'-Adenosyl)-L-
methionine as...

For the separation of trivalent actinides and lanthanides highly selective ligands are required. Soft N-donor ligands like bis(triazinyl)pyridines (BTPs) are known for their high separation factors. Though several investigations on the interaction of actinides with these ligands are available, the molecular origin of the selectivity remains largely unclear and is a topic of fundamental...

The ability to convert quantum states from microwave photons to optical photons is important for the hybrid system approaches to quantum information processing. The inverse transformation allows one to implement quantum memory of photon states based on electron and nuclear spins with a very long coherence storage time. The problem of quantum state conversion of microwave photons into optical...

Ubiquitination is a pivotal, multi-step, enzymatic post-translational modification that conjugates ubiquitin into chains onto protein substrates. Ubiquitination triggers a plethora of biological signals, and our focus is on protein homeostasis achieved through degradation of misfolded, unassembled, and highly regulated proteins in the ER. The specificity and mechanism of interaction between...

Understanding the function of a protein relies on the precise knowledge of its structure, dynamics and interactions. Pseudocontact shifts (PCS) have proven to be a valuable source of distance and angle-dependent restraints to monitor structural changes. DOTA-based lanthanide chelating tags (LCTs) have found numerous applications for the measurement of PCS on cysteine mutant proteins. A major...

Mechanochemistry offers an efficient and ecologically friendly way of preparation of new pharmaceutical cocrystals. On the other hand, structural analysis of the obtained crystalline forms can be troublesome, as the procedure does not yield crystals of sufficient quality for single crystal X-Ray diffraction experiments. In such cases solid-state NMR can offer a rich set of tools, which allow...

Paramagnetic NMR using lanthanide binding tags has proven to be very useful for structural characterization of proteins and strongly bound ligands in slow exchange. This is based on the distance and orientation dependence of pseudocontact shifts (PCS) induced by the paramagnetic center. A combination of NMR titrations and binding kinetics from other techniques such as AlphaScreenTM can be used...

CitA is a citrate sensing, membrane-bound histidine kinase. Despite significant progress in characterizing the structural and binding properties of its periplasmic citrate binding domain (PASp)^[1][2][3], the processes involved in transferring the citrate binding signal to the cytosolic domain (PASc) remain obscure. Crystal structures and COLD (Cryogenic Optical Locolization in...

Two- or multicomponent systems allow bacteria to turn various environmental stimuli into specific cellular responses including but not limited to development, cell division, metabolism and even antibiotic resistance. A typical two-component system consists of a sensory histidine kinase, which autophosphorylates a histidine in response to the input signal, and a transcription factor termed...

Rhodopsin belongs to the largest GPCRs (G-protein coupled receptor) membrane protein family in the human genome. Light absorption by rhodopsin is the initiation point for photoactivated signaling cascade in retinal rods. Point mutations in the protein sequence cause the disruption of the phototransduction resulting in the impaired visual cycle. G90 is a unique position, depending on the nature...

Magic angle spinning nuclear magnetic resonance spectroscopy (MAS-NMR) is a prevailing technique in case of structural/dynamic studies of membrane proteins directly in the native liposome environment. Here we demonstrate light-based toolboxes for MAS-NMR by which some intrinsic aspects of the lipid environment, such as membrane lateral pressure, can be changed and its effect onto membrane...

The purpose of this study is to investigate the lipid proton concentration in an obesity fatty liver so that the more accurate quantification of fat deposition can be performed by applying different lipid proton (LP) concentration changes using the multi-interference DIXON technique.
A high fat diet 60% was used to feed eight Sprague-Dawley rats in order to cause obesity fatty liver. Baseline...

Polymer electrolytes based on polyethylene oxide (PEO) were extensively studied in the past. However, they are still suffering from low ionic conductivity and low lithium transference number. Therefore, polyester-based electrolytes like poly($\varepsilon$-caprolactone) (PCL) have been investigated and were found to exhibit promising conductive properties, especially in a co-polymer with...

The local dynamics of a supercooled calcium rubidium nitrate melt is studied by nuclear magnetic resonance (NMR) using the strongly quadrupole-perturbed ⁸⁷Rb nucleus [1]: The ion dynamics is probed in the range from milliseconds to nanoseconds by central-transition stimulated-echo techniques, line shape analyses, spin relaxation, and second-order dynamic shift effects. The...

Long-lived nuclear spin state of the ¹⁵N pair in doubly ¹⁵N labelled trans-azobenzene have been studied. The singlet state of the two ¹⁵N spins is accessible due to magnetic non-equivalence¹. It is possible to convert ¹H or ¹⁵N magnetization to the long-lived state and backwards². The lifetime of the singlet order...

Dissolution DNP aims at enhancing the inherently low NMR sensitivity for nuclear spins using the high spin polarization of unpaired electrons. Especially preparation of hyperpolarized samples for in vivo MRI requires highest possible polarization of the target molecule in the shortest time possible. Transformation of dissolution DNP into a standard technique requires further progress in...

Especially in pharmaceutics, chirality has a high impact as enantiomers can have tremendously different effects on biological systems. To differentiate enantiomers in NMR, methods make use of chiral environments like chiral solvents, chiral solvating agents or chiral alignment media. A very well-known class of solvating agents are lanthanide shift reagents (LSRs) that have been developed until...

Adding nanosized fillers into a polymer matrix alters its mechanical properties from the behavior of the pure state [1]. We used static low-resolution $^1$H NMR spectroscopy to study model nanocomposites consisting of poly(ethylene oxide), mixed with spherical silica nanoparticles. Attractive interactions lead to slowing down of segmental motion and formation of an interfacial layer around the...

Asphaltenes, the heaviest, the most polar and the least reactive molecules in crude oil can aggregate and cause many problems during oil recovery and refining process. Asphaltenes isolated from the Middle East crude oil, atmospheric and vacuum residues were studied in this work.
It will be demonstrated that asphaltene aggregates form different molecular weight species with different...

Temperature monitoring is critical in MRI guided ablations to deliver necessary thermal energy to kill tumor cells while preventing damage to healthy adjacent organ tissue. The most popular tMRI technique, proton resonance frequency (PRF) based on the 0.01 ppm/^oC change in chemical shift of protons in water, fails in areas near or within adipose tissue. A minimally invasive MRI...

Manatee is a program written in Matlab that facilitates various types of statistical analyses of 2D NMR data by transforming a set of 2D spectra (or a selected region thereof) into a data matrix suitable for various analyses such as multivariate analyses (PCA, OPLS etc.) or a built-in peak correlation analysis. These types of analyses have several different applications when studying complex...

Human thioredoxin (Trx) is a major player in signal transduction that involves the post-translational modification S-nitrosation (SNO). The mechanism for Trx disulfide reduction activity is well-known and it occurs though the redox-active cysteines, Cys32 and Cys35. S-nitrosation activity is a gain of function in mammalians, which involves 3 redox-inactive cysteines, Cys62, Cys69 and Cys73,...

Intrinsically disordered presynaptic neuronal protein, α-Synuclein plays a critical role in synaptic vesicle trafficking, though the exact mechanism still remains unknown. It is also amyloidogenic in nature and deposits of higher aggregates of α-Synuclein in the Lewy bodies are the histopathological hallmark of second most prevalent neurodegenerative disorder, Parkinson’s disease....

We recently reported a previously unrecognized mitochondrial respiratory phenomenon. When ADP concentration was held constant (“clamped”) at sequentially increasing concentrations in succinate-energized muscle mitochondria in the absence of rotenone (commonly used to block complex I), we observed a biphasic, increasing and then decreasing, respiratory response, while membrane potential (ΔΨ)...

In order to distinguish the different consumable truffle species and to confirm their geographical origin, the metabolic profile of the fungi from the genus Tuber could store the answer within. To accomplish this task the polar extract of the fruiting body from authentic samples were analyzed by ¹H NMR spectroscopy under water suppression.^[1] The spectra of the different...

The strong ¹H-¹H dipolar coupling network of organic solids yields ¹H linewidths of few tens of kHz, orders of magnitude larger than those in solution. This homogeneous broadening is far greater than the isotropic chemical shift range and leads to broad and highly unresolved spectra from which very little information can be extracted.

Line broadening can be...

NMR is a powerful tool in early stage drug discovery. Its most prominent roles in the pharmaceutical industry are as a sensitive screening method for finding de novo hit matter or as an orthogonal biophysical method for confirming hits. Primary hit finding, and validation is most efficiently performed using ligand-observed experiments. The corollary of this approach is protein-observed NMR,...

Protein side-chain motions are essential for protein function. Methyl-bearing side chains have proven to be very useful probes of molecular motions [1]. Recently, we have combined high-resolution relaxometry and molecular dynamics simulations to study motions of isoleucine side chains with relaxation measurement of carbon-13 of $\delta$₁ methyl groups [2]. This novel approach gives...

Molecular assembly is cruel for improving our understanding of biological world and creating novel functional materials. How to realize controllable molecular assemblies is still challenging, and requires more propounding insights into the mechanism of assembly process, both thermodynamic and kinetic. However, the structures and components of assemblies are quite complex, which make their...

Mistic is an α-helical self-inserting integral membrane protein of B. subtilis triggering biofilm formation together with YugO, a K⁺-channel located downstream in the mstX-yugO two-gene operon^[1]. Its self-inserting properties attracted attention as a fusion tag to support production and incorporation of recombinant membrane proteins into lipid bilayers^[2]....

The function of a protein depends on both its structure and the internal dynamics of the peptide chain. Solid-state NMR is a one of the few techniques to determine ps to ms dynamics of large biomolecule complexes with atomic-resolution at physiologically relevant conditions. The development of fast MAS (>60 kHz spinning) has contributed to the ability to constrain the protein dynamics in at...

The centromere in eukaryotes is epigenetically marked by the presence of a specialised nucleosome wherein Histone H3 is replaced by a variant CenH3. In budding yeast, it is called Cse4. Cse4 has an unusually long N-terminal tail when compared to other CenH3s and the role of this long tail is not fully understood.
Since Cse4 is the component that distinguishes the specialized nucleosome from...

Over the last few years, the use of ionic liquids as co-solutes to modulate protein activity/stability or amyloidogenesis has attracted considerable attention. This is due to the large amount of possible cation/anion combinations that allow to develop tailor-made ILs with properties matched for specific applications - the control of protein stability or folding landscapes (Weingartner et al....

One of the main application fields of EPR in biological samples is the investigation of paramagnetic centers (like metal ions or amino acid radicals) in proteins. Electron-nuclear double resonance (ENDOR) allows obtaining information about naturally occurring, nuclear spins (¹H, ¹⁴N, …) in the immediate neighborhood of such electron spin centers. Interactions with remote...

Abnormal protein aggregation is a hallmark of Alzheimer’s disease and numerous other neurodegenerative disorders. Despite tremendous interest in pathogenesis of such diseases, no existing method can capture initial protein aggregate nucleation and subsequent growth at atomic resolution in real time.

To fill this gap, we have recently established high-sensitivity rheological NMR...

Molecular orientation distributions of polymeric fibers and films are known to be responsible for mechanical and electro-chemical properties. A quantitative interpretation of the molecular orientation distribution can be made by analyzing rotor phase separated CSA sideband intensities during slow rotation rates. The 2D rotor synchronized spectrum is matched with a theoretical model of the same...

Microalgae are increasingly studied in both academy and industry owing to their broad applicative potential. Indeed, they are able to create biomass with significant productivities compared to traditional crops. Besides, several microalgae species present the ability to produce lipids thanks to a metabolic shift provoked by nitrogen starvation conditions. In order to better understand this...

A key goal in biopharmaceutical development is to reduce costs and accelerate cell culture process development. Disposable single use bioreactors have aided the rapid development and manufacturing of drug products, but to further reduce costs and timescales, scale-down bioreactor systems have become popular. The ambr^TM system has gained much attention in recent years through the...

The development of the rapid scan technique was historically connected to the problem of the enhancement of the signal-to-noise ratio in NMR but it did not find wide application in NMR or EPR due to the rapid development of high power radio-frequency and microwave sources for pulse methods. However, the past decade is marked by the intense development of solid-state THz instruments, which has...

One of the most powerful features of nuclear magnetic resonance spectroscopy is the ability to address almost each element of the periodic table. Building up on this feature, addressing multiple nuclei simultaneously represents another source of information that NMR is capable to deliver, contributing to elucidate the structure and dynamics of a molecular system with atomic resolution. At the...

Surfactants are a group of chemicals, which lower the surface tension of liquids [1]. They may be completely unnoticeable, but we come across them in multiple different ways. They are used extensively in industry and science as detergents, wetting agents, emulsifiers, foaming agents and dispersants. However, these substances can also be found directly in our day-to-day life as they are used in...

Metal-organic frameworks (MOF) are attractive materials for gas storage and separation, catalysis, and sensing. Their high structural diversity and functionality are controlled by the use of a variety of organic linkers and metal ions. The possibility to incorporate paramagnetic metal ions into the framework, in particular, paves the way for future use of MOF in the field of molecular magnets...

Mussel glue-proteins undergo distinct structural responses during adhesion processes at the material interface by optimizing binding kinetics and multivalent surface contacts (Waite et al., Science 2015). Aspects of this intriguing behavior are mimicked by a mussel-glue mimetic peptide (HSYSGWSPYRSG (Y*=L-Dopa)) that has been previously selected by phage-display to adhere to Al2O3 after...

The self-assembly of organic molecules onto the surface of gold nanoparticles (AuNPs) provides a simple way to generate protecting monolayers that can incorporate molecular receptors. By exploiting different kinds of non-covalent interactions (namely hydrophobic, ion pairing, and metal−ligand coordination) such receptors can in turn provide tailored host sites for virtually any class of guest...

Contrary to the view based on the classical random coil model, it is now clearly established that individual amino acid residues in unfolded peptides and proteins differ with regard to their conformational propensities. The prime example is alanine which shows a very high preference for polyproline II (pPII). Recently, our research groups conducted a conformational analysis of GxyG host-guest...

Deep neural networks (DNNs) offer a powerful alternative to Tikhonov regularised analysis procedures for standard DEER data. DNNs can be trained on libraries of synthetic DEER traces, allowing them to learn a simulated reality which can include carefully modelled distortions and noise – we have shown that DNNs trained in this manner generalise well to real experimental data. [1]

The...

We discuss a novel isotope-labeling approach to improve the ¹H_α resolution and to simplify side-chain ¹H signals for ¹H-detected protein solid-state NMR (SSNMR) with a simple bio-expression method using E. coli. SSNMR using ¹H detection is attracting attention as a powerful method for protein structure determination. However,...

Although the incidence of Alzheimer’s Disease (AD) increases¹, the underlying mechanisms of the neurodegenerative process are still not understood. In vivo magnetic resonance spectroscopy (MR) is ideally suited for investigating of neurochemical disease processes, due to its non-invasive combination of chemical sensitivity and imaging. So far, however, significant magnetic resonance...

Solid-state NMR has played an important role in structural analysis of various insoluble and heterogeneous biomolecules such as amyloid fibrils. The lack of spectral resolution, however, still poses a serious problem. Although multi-dimensional experiment can potentially enhance spectral resolution, higher dimensional SSNMR experiments beyond 4D are challenging due to exponential increase of...

Dynamic Nuclear Polarization (DNP) has recently established itself as a valuable technique to enhance the sensitivity of solid-state NMR spectroscopy. Over the years, sample formulations have been carefully optimized for intermediate magnetic fields (9.4 T), where DNP equipment is commercially and readily available to scientists in the field. An extensive list of polarizing agents has been...

In general, structure and function of biomolecules can be strongly influenced by their environment. This is in particular true for membrane (associated) proteins and soluble proteins inside a densely-packed cell. Modern structural biology therefore requires advanced biochemical tools to generate adequate complex environments as well as techniques that can be used in these environments and...

Transportation of cellular cargo towards the minus end of microtubules is mediated by specific adaptors that engage with dynein to recruit and activate the motor. Malfunction of this machinery is known to cause diseases such as tumors and spinal muscular atrophy, but the molecular mechanisms remain incompletely understood.
Here, we use structural and dynamics nuclear magnetic resonance (NMR)...

NMR spectroscopy and molecular dynamics are ideal tools to investigate intrinsically disordered proteins (IDPs), difficult to study by other structural methods. Recent literature documents that force-fields developed for well ordered proteins fail to simulate molecular dynamics of intrinsically disordered proteins (IDPs) realistically. In particular, parameters of the water model need to be...

In recent years, the concept of noncovalent bonding has expanded to include a specific and interesting class of interactions analogous to hydrogen bonding, called σ-hole interactions.[1] These interactions result from the depletion of electrostatic density on the opposite end of a covalent bond between an electron-withdrawing substituent and a ‘donor’ atom from groups 14-17 in the periodic...

The 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane commonly named pentaspiroglycol (PSG) or spiroglycol (SPG) is a high molecular weight rigid alicyclic diol widely used in the chemical industry. SPG has no hazardous classification, it is not mutagenic and is a safe alternative to Bisphenol A, a well-known chemical which is rising concern due to his proved endocrine...

Ellagitannins, a sub-class of hydrolysable tannins are widely distributed polyphenolic plant secondary metabolites that have shown various antiherbivore and antiparasitic as well as human health-promoting activities [1–3]. In many cases, their relatively complex chemical structures combined with difficulties in purifying reasonable amounts of pure compounds set challenges to their structure...

Glycans serve as recognition elements for glycan binding proteins at the surface of most cells and mediate key biological processes such as cell-cell adhesion, migration and other events critical for the development and function of complex multicellular organisms. At the heart of important living processes, protein-glycan interactions are also linked with several diseases, including infection,...

Tuberculosis is one of the deadliest diseases, affecting approximately 10 million people in 2017. This classifies tuberculosis as epidemic in several countries and lead to an increasing number of multidrug-resistant strains. Thereby, the development of new drugs is essential to effective treatments. The ribose 5-phosphate isomerase (Rpi) catalyzes the interconversion of D-ribulose-5-phosphate...

Endofullerenes are supramolecular complexes where one small (endohedral) atom/molecule is confined within a bigger, fullerene, molecule which acts as an enclosing cage.$^1$ Endofullerenes offer an ideal particle in a box system to observe quantum mechanical effects.

C$_{60}$ is an irregular truncated icosahedron, with two bond types in 2:1 ratio.$^2$ Ever since its discovery, the solution...

Riboswitches are a class of RNA regulatory elements that are located in the 5´-UTR (untranslated region) of genes. Upon binding of small molecules, riboswitches undergo a structural rearrangement preventing the formation of terminator or antiterminator elements regulating the transcription of the downstream genes. The secondary messengers c-di-GMP (3′,5′) enables terminator formation off the...

Hsp70 and Hsp90, two central chaperones of the heat shock protein (Hsp) family, play an important role in maintaining protein homeostasis [1]. In addition to their discrete chaperone function, they can build up the Hsp70/Hsp90 chaperone machinery where Hsp70 is linked to Hsp90 via the Hsp-organizing protein (Hop) [2, 3, 4]. It is well known that Hop can bind simultaneously to both chaperones...

The availability of antibiotics has allowed for the successful treatment of many bacterial infections as well as the ability to perform invasive medical procedures including surgery and chemotherapy. However, their wide use has led to pathogens' increased drug resistance and the need to find novel classes of antimicrobial peptides as alternatives to antibiotics. Lactophoricin (LPcin), a...

TGF-β stimulates the proliferation and differentiation of regulatory T-cells (T_regs) to promote peripheral immune tolerance. The mouse parasite Heligmosomoides polygyrus manipulates the host immune system through the induction of Fox3p+ T_regs using the five-domain complement control protein (CCP) protein, TGM. Though lacking any homology to the TGF-βs, TGM binds directly...

The lipoprotein signal peptidase II (LspA), a membrane protein, is a key enzyme in Pseudomonas aeruginosa, a human pathogen. Its substrate are lipoproteins of the bacterium. The antibiotic globomycin inhibits LspA. The goal of the project is to gather structural information related to LspA inhibition and lipoprotein processing. From recent structural studies by crystallography and solution...

Biological membranes are made up of phospholipids, which form a bilayer structure along with proteins and carbohydrates. In order to study the behaviour of these membranes, phospholipid vesicles have long been used as models. Whilst they may be a far cry from the complexity of a cellular membrane, their simplicity allows researchers to study individual biophysical effects in isolation....

Catalytic processes are ubiquitous appearing in nature and are also important for chemical industry. Understanding these can help to develop better and more efficient catalytic systems. NMR has proven to be a very powerful tool to investigate these processes by detection of intermediate species or by studing reaction kinetics. Recently, we have used PHIP NMR methodologies to obverse ruthenium...

Transcription factors are proteins that bind specific sites or elements in regulatory regions of DNA, known as promoters or enhancers, where they control the transcription or expression of target genes. Homeobox genes, of which the most well-characterized category is represented by the HOX genes, play a crucial role in normal development. MEIS1 (myeloid ecotropic viral insertion site 1) is a...

Synthetic polymeric hydrogel have attracted huge attention due to their unique properties as a 3D crosslinked network as well as their various applications in tissue engineering scaffolds and bio-sensors. Among all the synthetic polymeric hydrogels, polypeptides shows excellent suitability for hydrogelating materials as they possess a number of desirable properties. Besides their side chain...

Historical and cultural-heritage buildings were mainly built of stone or a mixture of stone and brick, using lime-based mortars. Because of poor quality of the used mortar and the presence of voids in the walls, the load bearing capacity of such walls is mostly insufficient and the buildings deteriorate in the course of time. An efficient technique for the repair and/or strengthening of the...

Pyridine derivatives are of high interest in medicinal chemistry as well as SABRE hyperpolarization studies. Therefore, the stability is very important. Here, we have investigated the stability of several pyridine derivatives fluorinated in 2-position. Some of the substrates were examined previously but without NMR spectroscopic measurements.^[1-4] It is well known that e.g....

Soluble Guanylate Cyclase (sGC) is the primary receptor for nitric oxide (NO) and a potential therapeutic target. sGC has a key role to essential and diverse physiological processes such as blood pressure regulation, memory formation, platelet aggregation and muscle relaxation. sGC is a heterodimeric hemoprotein which consists of an H-NOX domain, a Per/ARNT/Sim (PAS) domain, a coiled-coil (CC)...

Transcription is the first step of gene expression, and RNA polymerase specifically copies a particular part of DNA into mRNA. Transcription Factor (TF) is a protein that controls the rate of transcription by binding to a specific DNA sequence. Of the transcription factor protein, we studid Drosophila distal-less homeobox (DLX) gene. Genes in the DLX family encode homeodomain transcription...

Investigation of systems in evolution such as chemical reactions via NMR can be rendered comfortable if the intrinsic lack of sensitivity of this technique is circumvented and provided that quantitative data are obtained.
Here we present an integrated device based on a 3D-printed mini bubble-pump associated with fluidics and micro-detection that overcomes the sensitivity problems inherent to...

Fragment-based drug discovery is an essential strategy in the development of new clinical candidates. Both NMR and crystallography-based fragment screening can be applied to detect binding. A challenge in early-stage drug discovery is to acquire enough structural information on fragment placement in order to drive compound development. Crystallography may provide such information. However,...

The metabolism of plants has evolved several different strategies to cope with different types of abiotic stresses, ranging from reconfiguration of central metabolic pathways such as carbon, nitrogen and energy metabolism, to biosynthesis of specialized secondary metabolites. The plant circadian clock is intimately connected with plant response and tolerance to abiotic stress. We performed...

The metabolic syndrome, which is becoming increasingly important especially in western industrial countries, involves four disorders: fat metabolism, sugar metabolism, fat conductivity and high blood pressure. A healthy lifestyle including a healthy diet should minimize the risks of disease. Several metabolic pathways play an important role in the etiology of the metabolic syndrome, especially...

Nuclear Magnetic Resonance is widely used for qualitative as well as quantitative evaluation of chemical compounds. For chemists, it is particularly valuable tool providing an insight into reactions and allowing to study their mechanisms. An interesting case is the observation of intermediate products that can not be observed in the post-reaction mixture. Often, changes in their chemical...

Among various NMR tools designed for the analysis of small molecules, two-dimensional (2D) experiments are particularly informative. Unfortunately, they are usually too time-consuming to serve as a "snapshot" technique forreaction monitoring. The process occurring in the sample will not stop just because spectroscopist needs more time to acquire the data. In fact, even if one can control the...

Laplace NMR (LNMR), comprising of relaxation and diffusion experiments, provides detailed information about molecular rotational and translational motion. The resolution and information content of LNMR can be increased substantially by a multidimensional approach. However, the approach leads to very long experiment times due to need for repetitions with an incremented evolution time or...

Riboswitches belong to the group of sensory RNA motifs that are able to form two different conformations in response to physiological signals like differing metabolite concentrations. While the RNA adopting one conformation will encourage expression of the associated genes, adopting the other one leads to termination of either transcription or translation. Until today, various metabolites...

Various baseline correction methods for Nuclear Magnetic Resonance (NMR) spectra, such as polynomial fitting, smoothing, and Asymmetric Least Square (ALS), have been proposed. ALS is a highly accurate and semi-automated method, but this has heavy dependence on hyper-parameter $\lambda$. Smoothing is a classical method, but Automated Iterative Moving Average (AIMA) which is one representative...

Photoactive chemicals have received considerable attention because of its interesting applications[1]. Singlet state NMR properties as response to light induced processes have attracted our attention. Nuclear spin singlet states consist of two spin-1/2 nuclei coupling into a resulting spin-0 state[2]. The key feature of singlet states is they are immune to intramolecular dipole-dipole. As a...

Nuclear spin singlet states consist of two spin-½ nuclei and form a spin 0 which can only be probed indirectly[1]. The equilibration time (T_S) between the triplet and singlet state often exceeds the longitudinal relaxation time T₁[1].

We are going to present our recent investigations on using the singlet phenomenon as contrast mechanism. In initial experiments we have...

Helium prices are skyrocketing as the supply of helium from the United States is decreasing. For this reason, bench-top NMR of permanent magnets that do not require helium is beginning to spread. Since a permanent magnet is difficult to generate a magnetic field of 2 T or more, a cryogen-free superconducting magnet will be required in the future. Since we have developed a cryogen-free...

NMR is a very powerful tool to study weak protein-ligand interactions exhibiting dissociation constants in the 1 µM – 1 mM range. This weak binding is usually associated with fast ligand off-rates. One of the most widely used NMR technique to study such complexes is the measurement of chemical shift perturbation upon binding. This is being used to map the residues in the binding protein...

The ⁹¹Zr SSNMR has become a useful tool for structural studies of crystalline systems, for example zirconocenes and zirconium-containing metal–organic frameworks, despite of a low natural abundance (11.2%) and receptivity (1.07E–3 relative to ¹H), and a quite high quadrupole moment (–0.176E–28 m²), of the ⁹¹Zr(I=5/2) nucleus. However, the...

We achieve one-dimensional nanoscale localization of the nitrogen-vacancy (NV) defect centers in diamond by means of phasing encoding approach under gradient magnetic field. Coplanar and gradient micro-wires deposited on the diamond surface are connected in series with a power supply and voltage controlled current source. Magnetic gradient fields for NV centers phase encoding are produced by...

Recently, Magnetic Resonance Imaging (MRI) has strongly advanced its performance by Dynamic Nuclear Polarization (DNP) methods. One of them is a continuous flow of hyperpolarized substrate produced by a DNP polarizer placed directly inside the bore of a 1.5 T MRI scanner [1,2]. Here we present a new open Fabry-Perot resonance structure with a 4-fold increased flow rate of hyperpolarized...

NMR signal is usually measured using induction in a coil around the sample. However, it has been shown that nuclear magnetization can also be detected using optical methods sensitive to the polarization of light [1]. Such methods might, for example, employ nuclear spin-induced circular dichroism (NSCD), one of new theoretically predicted nuclear magneto-optic effects [2].
In its essence, NSCD...

The method of optically detected magnetic resonance (ODMR) was used to observe spin transfer processes from the paramagnetic Gd³⁺ and Tb³⁺ ions to Ce³⁺ emitters in garnet crystals. The intensity of photoluminescence excited by circularly polarized light into Ce³⁺ absorption bands can be used for selective monitoring the population of the...

Overhauser Dynamic Nuclear Polarization (DNP) is a powerful technique for improving the signal-to-noise ratio of liquid state NMR. It usually uses microwaves to saturate the EPR transitions in radicals, which, owing to cross-relaxation, results in polarization transfer to nuclear spins. An alternative approach has recently been demonstrated, using visible light to generate triplet states of a...

Overhauser Dynamic Nuclear Polarization (ODNP) is employed to solve the premagnetization issue in continuous flow Nuclear Magnetic Resonance (NMR) spectroscopy. This might enable monitoring of very fast chemical reactions and processes, which is important in chemical engineering. NMR detection is performed with a mobile, medium-field NMR spectrometer (benchtop, 43 MHz proton frequency) due to...

Chemical activation of parahydrogen molecules plays a key role in parahydrogen-based hyperpolarization techniques. Commonly, metal-containing activators/catalysts (complexes, nanoparticles, oxides) are employed to mediate such activations and produce hyperpolarization in parahydrogen-induced polarization (PHIP) as well as in signal amplification by reversible exchange (SABRE). Signal...

Paramagnetic NMR is a direct probe of electronic structure in many coordination compounds and organometallic systems. Unpaired electrons alter the NMR spectrum of the surrounding nuclei causing paramagnetic shifts and relaxation enhancements which report in a direct way on the structure of the compounds and configuration of the chemically active molecular orbitals. Such effects can nowadays be...

Pulsed dipolar electron paramagnetic resonance spectroscopy (PDS) in combination with site-directed spin labeling (SDSL) is a powerful tool in structural biology. It can be applied to biomole-cules in vivo, does not require crystallization and can thus provide information on structure and dynamics in the native environment.^{[1, 2]}

To date, the most widely employed type of spin...

High-field magnetic resonance is an extremely powerful characterization technique, which cannot however be trivially adapted to perform in in operando studies in technological materials like porous solids. Limitations with space, radio-frequency compatibility, transportability and maintenance are some of the difficulties one has to fight against. On the other hand, low-field magnetic resonance...

We use state-of-the-art NMR experiments to measure apparent pKa values in the native protein environment and employ a cutting-edge combination of enhanced sampling and constant pH MD simulations to rationalize strong pKa shifts. Phl p 6 serves as an ideal model system for both methods due to its high number of titratable residues despite its comparably small size. Combining microscopic...

Alzheimer’s disease (AD) is associated with deposition of misfolded aggregates of Amyloid-β (Aβ). The Aβ(1-42) peptide is the most aggregation prone compound in senile plaques of AD patients and more neurotoxic compared to the shorter peptide Aβ(1-40). Recently, high-resolution 3D structures of different polymorphic Aβ(1-42) fibril types have been determined by solid-state NMR spectroscopy as...

The increasing demand for high capacity yet safe storage of renewable energy calls for the development of all-solid-state batteries. To utilize these solid-state batteries to their full potential, a new type of electrolyte has to be developed. Nanoconfined lithium borohydride is a candidate solid-state electrolyte due to its high lithium mobility at ambient temperatures. The origin of the high...

Electrophoretic NMR (eNMR) is a versatile method for the investigation of drift velocities of charged and neutral species within an electric field. The application of an electric field during a diffusion NMR experiment causes a zero order phase shift of the NMR signal depending on the parameters of the diffusion experiment and the applied electric field strength. However, the experimental...

The nuclear factor of activated T-cells (NFAT1) is arguably the most important transcription factor in the immune system. NFAT initiates immune response by up-regulating the production of several cytokines (IL-4, TNF-alpha, IFN-gamma, etc.). Besides its prominent role in infectious disease response as well as e.g. organ transplant rejection, NFAT has been linked to a number of mechanisms...

Photo–induced reactions have (again) become rather popular within the recent years. NMR, CIDNP, and EPR providing information at the molecular level have been utilized as ideal methods for following such reactions. 1-2
We have investigated electron-transfer processes in phospholipid membranes using EPR establishing the corresponding rate constants. In terms of NMR, we have performed...

Photo-thermo refractive (PTR) glasses are photosensitive glasses of composition 70SiO$_2$•15Na$_2$O•5NaF•5ZnO•4Al$_2$O$_3$•1KBr that are doped with small quantities of CeO$_2$, Ag$_2$O, Sb$_2$O$_3$, and SnO$_2$ (0.01 mol %). Their refractive index can be modified with high spatial resolution using focused UV irradiation and subsequent annealing close to the glass transition temperature. This...

Photoirradiation solid-state NMR spectroscopy is a powerful means to study photoreceptor retinal-binding membrane proteins by the detection of short-lived photointermediates to elucidate the photoreaction pathways and photoactivated intermediates. An in situ photoirradiation solid-state NMR apparatus has been developed for the irradiation of samples from inside a sample tube with extremely...

Rod-shaped compounds with a five-membered ring nitroxide radical (NR) moiety in the mesogen core show unique intermolecular magnetic interactions in their liquid crystalline (LC) and isotropic liquid (Iso) phases above room temperature; their paramagnetic susceptibilities often rise steeply at phase transitions from crystalline (Cr) to LC phases [Y. Uchida et al., J. Mater. Chem., 2008,...

Fifteen elements of lanthanide group plus Yttrium and Scandium are known as Rare Earth Elements (REEs). Because of their unique physicochemical properties (e.g. fluorescence, phosphorescence, …), they have a wide range of applications in technology [1-3]. Phosphate minerals are known as potential resources for REEs. Because of low percentage of these elements in phosphate minerals, deeper...

Most food products are irradiated by ionizing radiation for sterilization purposes. Electron Paramagnetic Resonance (EPR) is the only technique that allows the direct determination of the paramagnetic centers that ionized radiation can form in the structure without damaging the sample. Using the EPR technique, it is possible to determine the effects of radiation on food, whether it is...

PHIP (Para-Hydrogen Induced Polarization) is one of the most useful and cost-efficient methods of creating nuclear spin hyperpolarization. Signal enhancement in the PHIP method comes from the non-equilibrium nuclear spin order of the parahydrogen molecule. PHIP does not require expensive equipment and allows amplification of NMR signals by approximately a factor of 10⁴, making it...

Much work in the field of parahydrogen-enhanced NMR involves the transfer of proton polarization to heteronuclei using the molecular J-coupling network. Techniques such as magnetic field cycling [1] and ‘SABRE-SHEATH’ [2] have emerged for this purpose. We recently presented a new technique: a molecule containing a heteronuclear spin is hydrogenated with parahydrogen at some magnetic field to...

In literature self-reporting particles, for example with an optical sensing response, are being developed [1-2]. Despite well-reported optical properties and reactions of polyionic liquid inverse opal microspheres (PIL-IOMS), the underlying structural changes in this hierarchically porous material are underexplored. In this work PIL-IOMS were used, whose water content and therefore their pore...

RNA-protein complexes are involved in multiple cellular functions and vary with regard to affinity and specificity. Both double stranded and single stranded RNA chains can be observed in complex with proteins. Here we develop methods based on PRE-measurements to elucidate the process of RNA recognition by the ribosomal protein S1, involved in translation initiation. In the past chemical shift...

Ceramide, an important component in the metabolism of sphingolipids, plays a significant role in proliferation and apoptosis of cells.1 De novo synthesis of ceramide takes place at the cytosolic surface of the endoplasmic reticulum (ER), and then ceramide is transferred to the Golgi apparatus for conversion into sphingomyelin and glucosphingolipids, mainly by non-vesicular trafficking....

G protein-coupled receptors (GPCRs) are versatile chemical sensors, which transmit the signal of an extracellular binding event across the plasma membrane to the intracellular side, leading to the activation of downstream effector proteins.¹ This function is achieved via the modulation of a highly dynamical equilibrium of various conformational receptor states.^2,3...

Host−guest interactions between adsorbed molecules and active sites on catalyst strongly influence catalytic performances (activity and selectivity) because they play essential roles in the reactant adsorption, intermediate formation, and product desorption. The methanol-to-olefins (MTO) conversion on acidic zeolite catalysts provides an alternative to produce lower olefins from decreasing...

Amyloid fibrils are β-sheet-rich protein aggregates commonly found in the organs and tissues of patients with various amyloid-associated diseases.1 An aggregated form of the human islet amyloid polypeptide (hIAPP) is believed to be associated with β-cell death in type-II diabetes (T2D). Environmental elements of β-cell granules including high concentrations of insulin are known to inhibit IAPP...

α-synuclein aggregates are a hallmark of Parkinson’s Disease (PD). Modulation and understanding of the toxic species is, therefore, a key goal in disease treatment. The small molecule anle138b, a 3,5-diphenyl-pyrazole derivative, has shown efficacy in PD animal models.[1] Here we report the interaction of anle138b embedded in phospholipid membranes, with α-synuclein aggregates. We used...

Here, we use magic angle spinning dynamic nuclear polarization (MAS DNP) NMR spectroscopy methods to unambiguously elucidate the interface between aluminum containing-adjuvants and the associated phospholipid-bound antigens.
In particular, we exploit the potential of MAS DNP to implement sophisticated heteronuclear correlation experiments such as $^{31}$P-$^{27}$Al scalar and dipolar INEPT...

ATP-binding cassette (ABC) transporters regulate the human biological systems through the trafficking of endogenous components (e.g. lipids, vitamins, steroids, and metabolites) and exogenous compounds (e.g. drugs). They are known for their critical role in multidrug resistance (MDR) in human cell derivatives and diseases (e.g. cancer, Alzheimer’s disease, atherosclerosis), as well as in the...

Methodological and technological advances in EPR spectroscopy have enabled novel insight into the structural and dynamic aspects of spin-labeled integral membrane proteins. In addition to an extensive toolkit of EPR methods, multiple spin labels have been developed and utilized, among them Gd(III)-chelates which offer high sensitivity at high magnetic fields. Here, we applied a dual labeling...

A protein’s environment is often key to understanding its structure and function. However determining the environment of a membrane protein at atomic resolution is difficult by most techniques used in structural biology. We present a method to site-specifically probe water- and lipid proximities in membrane proteins at a resolution of ~3 Å using magic-angle spinning (MAS) NMR spectroscopy...

Low-field NMR relaxometers are powerful instruments as they can be moved outside the laboratory to be closer to the sample (in fields or next to a production line), for on-line quality control for example. Open-magnets present the advantages of (i) being slice selective and (ii) able to record 1D NMR profile if the magnet is mounted on a high-precision lift. The NMR-MOUSE is an example of a...

We have previously shown that bullet-dynamic nuclear polarization (bullet-DNP) can achieve liquid-state ¹³C polarization levels of 30% at less than 10-fold dilution with sub-mL solvent volumes as used in NMR spectroscopy [1].

Low-field thermal mixing [2] has the potential to rapidly polarize low-gamma nuclei, without the need for strong B1 fields at cryogenic temperatures....

Non-covalent interactions, such as hydrogen bonds, van-der-Waals or ionic interactions are of key importance in catalytic processes and play an important role in molecular recognition. We present a combined approach based on $\mathrm{^{1}H}$- and $\mathrm{^{31}P}$-detected Magic-Angle Spinning (MAS) experiments to identify protein-nucleotide contacts in the bacterial DnaB helicase from...

The M2 protein from influenza is a membrane protein that forms a tetramer and acts as a proton channel. M2 inhibitors cause large conformational changes upon binding.¹ A histidine cluster (His 37) localized in the middle of the pore has been identified as a main component of the proton shuttle mechanism. However, the histidine cluster has been reported as structured in either a box...

We here use the hepatitis B virus capsid made from the core protein as a model to establish approaches allowing to investigate conformation, assembly and interactions in large protein complexes. We have previously demonstrated that HBV capsids produced in E. coli can be studied by solid-state NMR at high resolution and sensitivity using ¹³C-detection experiments^1,2.

We...

PsbO is an extrinsic subunit of the Photosystem II (PSII) complex and is known to act as 'manganese-stabilizing protein'. It is the only extrinsic protein of PSII that is present in all photosynthetic organisms. PsbO plays a central role photosynthesis and has therefore been studied over many decades. Its molecular mechanisms remain to be fully elucidated. PsbO has been suggested to...

Fine particulate matter with an aerodynamic diameter less than 2.5 μM (PM_2.5) is one of the most important air contaminants. The exposure to PM_2.5 could cause pulmonary oxidative stress, inflammation, and thickening of the alveolar wall. The conventional methods including bronchoalveolar lavage fluid (BALF), synchrotron radiation X-ray fluorescence, and histopathological...

We propose a solution to the matrix dimension problem in quantum mechanical simulations of MRI experiments on complex molecules. This problem is very old; it arises when Kronecker products of spin operators and spatial dynamics generators are taken – the resulting matrices are far too large. However, spin and spatial operators individually have manageable dimensions, and the action by their...

The combination of solid-state NMR and crystal structure prediction has shown to be a powerful method to elucidate the structure of amorphous materials and microcrystalline solids: one of the key challenges in chemistry today. However, two main downsides currently prevent efficient high throughput structure elucidation using this approach: (i) the high computational cost associated with CSP...

SPatiotemporal ENcoding (SPEN) is an ultrafast technique that relies on frequency swept pulses combined with readout gradients to collect 2D images of a sample in a single scan with fewer distortions than EPI. SPEN achieves this at the expense of a higher SAR (power deposition) associated to the use of the widely swept RF pulses. The present study presents a way to extend 2D SPEN scans to 3D...

Over the years Dynamic Nuclear Polarization (DNP) has developed into a powerful method for sensitivity enhancement of NMR. At high magnetic fields, DNP in the solid-state is particularly effective. This has led to the successful implementation of cryo-MAS DNP for studying proteins and materials and dissolution DNPin a clinical setting. However, the application of DNP to chemical analysis of...

Since the last 15 years MAS-DNP has developed into an important research tool in the structural investigation of materials and surface science. The sensitivity gain is provided by highly polarized electron spins transferring polarization to nuclear spins upon microwave irradiation. The polarizing agent (PA) is represented typically by exogenous radicals with the gold-standard bis-nitroxides...

CO2 absorption in a series of choline-based ionic liquids is investigated using solid-state 13C and 15N MAS NMR spectroscopy [1]. Natural abundance and 13C enriched CO2 gas was purged through 50 wt % aqueous solutions of alkyldimethyl(2-hydroxyethyl)ammonium threonine, [N1,1,n,2OH][Threo], (alkyl = butyl, pentyl and hexyl) and pentyldimethyl(2-hydroxyethyl)ammonium taurine [N1,1,5,2OH][Tau]....

Because they follow non-classical crystallization mechanisms, many biomineral nucleation processes remain the subject of intense debated [1]. It has been proposed that in many cases soluble prenucleation inorganic species can evolve through aggregation to form their mineral solid phases. To adequately understand the formation of biominerals, new analytical approaches are needed, to allow...

NMR spectroscopy is a powerful tool for the monitoring of organic chemical reactions. Multidimensional experiments have the potential to bring more information on reacting mixtures, but the duration required for classic experiments (several minutes) limits the accessible timescales. Ultrafast 2D NMR, originally proposed by Frydman in 2002 (1), makes it possible to collect 2D spectra in less...

A key feature of NMR is that information is accessible at atomic resolution. However, ambiguities arise if signals overlap and, therefore, great effort has been made to increase either signal dispersion (e.g. high magnetic fields, n-dimensional NMR, detection of heteronuclei) or to reduce signal width (e.g. pure shift NMR, TROSY). Despite the fact that individual homonuclear couplings might...

The encapsulation of active ingredients in liposomes is used in several domains such as food, pharmaceutical and cosmetic industries. Liposomes are drug delivery systems (DDS) used both for lipophilic cargos and for hydrophilic cargos. Such encapsulation allows a controlled release of active ingredients over time [1].
To increase the efficiency of peptide drugs, we aim at designing optimized...

REDOR and DIPSHIFT are two of the most commonly used experiments to determine dipole-dipole couplings (DCs) in solid-state MAS-NMR. Their robust performance with respect to experimental settings and the direct dependence of their dephasing profiles on a single variable - the DC, makes them highly attractive for studying a wide range of samples. Both these experiments achieve heteronucler...

Speeding-up NMR molecular analysis is an important research field which has been continuously advancing since NMR early days. The relevant benefits are clear and evident:

• Reduce the time per analysis directly reduce its cost
• Gaining spectrometer time to analyze new samples

Many interesting tools and concepts have been appearing in last decades. Concretely, our experience focuses on the...

Natural products play a critical role in drug discovery as they provide access to new chemotypes and structural diversity. In order to take advantage of natural products as potential drug candidates, their exact chemical structure and configuration need to be known. Structure and configuration determination can be achieved by X-ray crystallography if sufficient material is available and...

Fluorine-19 seems to be an ideal target for site-specific studies of biomolecules: it has a gyromagnetic just below the one of proton, 100% natural abundance, a large chemical shift dispersion and offers a background-free signal in biomolecules. However, its large chemical shift anisotropy (CSA) leads to transverse relaxation rates too high for standard multi-dimensional NMR (transverse...

Objective of the study was to compare relaxation properties of theranostic paramagnetic liposomes prepared by two distinct preparation methods, that is thin lipid hydration (TLH) and microfluidic method (MM). Liposomal formulations were prepared with Zn-Phthalocyanine (ZnPc) a highly hydrophobic model photosensitizer, incorporated within lipid membrane with or without PEG moieties, composed of...

Due to the increasing demands for large scale grid energy storage, sodium metal batteries (SMBs), are competitive for economic and environmental reasons. Stabilizing the reactive metal anode is a critical challenge for the development of SMBs. Our work demonstrates that sodium-difluoro(oxalato)borate (NaDFOB)-based carbonate-ester electrolyte possesses favourable electrochemical stability and...

The evaluation of the natural isotopic profile of (bio)-compounds is an ongoing challenge for the authentication/determination of their origins or to understand their metabolic/synthetic pathways. In the field, the 2H SNIF-NMR® protocol has been developed around the quantitative 2H-{1H} 1D-NMR spectroscopy at natural abundance level (NAD NMR) in isotropic solvents to study the Site-specific...

Alternate structural conformers are the foundation of “protein evolvability”, which refers to the aptitude of proteins to rapidly adopt new functions within existing folds or even adopt entirely new folds. The understanding of protein evolution depends on the ability to relate the impact of mutations on molecular traits to organismal fitness. Antibiotic resistance mediated by β-lactamases...

A nitroxide spin label has been covalently attached to the weak polyelectrolyte poly(ethylene-alt-maleic acid) (P(E-alt-MA)) to study the rotational dynamics of the polyacid backbone in swollen polyelectrolyte multilayers (PEMs) formed by P(E-alt-MA) and the oppositely charged weak polycation poly(allylamine hydrochloide) (PAH) by continuous wave (CW) electron paramagnetic resonance (EPR)...

Structure and dynamics of organic molecules-ligating clusters significantly influence the optoelectronic property and function of the clusters as well as their stabilization. Recently, we revealed that, cysteine capping on (CdSe)₃₄ magic-sized cluster (CdSe-Cys) has two capping structures: monodentate ligand-cysteine with sulfur–cadmium bond and bidentate one with sulfur– and...

NMR and MRI techniques enable to derive structural information on porous materials from the study of restricted self-diffusion. The condition to make diffusion a source of such information is to track the displacement of a molecular probe long enough for this to experience the confinements. Since diffusion Magnetic Resonance techniques rely on the acquisition of a signal whose decay constant...

Dynamic Nuclear Polarization (DNP) is a powerful method for sensitivity enhancement during solid-state NMR experiments. One recently discovered mechanism in DNP is Specific Cross-Relaxation Enhancement by Active Motions (SCREAM-DNP). SCREAM-DNP can be observed when molecular motions support the specific condition for heteronuclear cross-relaxation between ¹H and ¹³C,...

NMR is a powerful tool to unravel the molecular dynamics in viscous liquids, polymers, and melts. Most of the applications in this field focus on organic materials and typically they employ spin-1/2 nuclei. Conversely, for many inorganic glass formers one has to use compounds for which quadrupolar interactions prevail. Here we explore the static and dynamic properties of liquid and glassy...

Applications of ionic liquids (ILs) are continuously expanding. Current applications include ILs as electrolyte material in lithium batteries, ultracapacitors, media for chemical reactions, drug delivery systems. The potential of ILs lies in the flexibility and customisation due to chemical variability of their components. That being said, the properties of ILs are tailored via the selection...

The determination of the enantiomeric purity of chiral drug molecules is an important task involving rigorous regulatory demands in the pharmaceutical industry. Besides chiral HPLC and CE, NMR spectroscopy is a widely applied method for this purpose. It is commonly held that in order to separate the NMR signals of enantiomers so that they can be individually integrated, diastereomeric...

Abstract

Nanoparticle-assisted NMR chemosensing exploits the recognition abilities of gold nanoparticles in solution to detect and identify specific classes of molecules in multi-analyte mixtures. The nanoparticle-analyte recognition event is exploited to induce a selective magnetization transfer via the nuclear Overhauser effect from the nanoparticle’s monolayer to the interacting...

Solid-state NMR analysis of biological samples has continuously been hampered by a lack of sensitivity. Especially complex multidimensional experiments suffer from a low signal-to-noise ratio as a consequence of low coherence transfer efficiencies. One reason for less than optimal magnetization transfers is the RF inhomogeneity of solenoids commonly used for excitation and detection in MAS...

The structural basis of minor groove recognition of a DNA duplex containing synthetic genetic information by hairpin pyrrole-imidazole polyamides is described. Hairpin polyamides induce a higher melting stabilization of a DNA duplex containing the unnatural P·Z base-pair when an imidazole unit is aligned with a P nucleotide. An NMR structural study showed that the incorporation of two isolated...

SIFTER¹ (single-frequency techniques for refocusing) is a single frequency pulsed EPR method similar to PELDOR² for studying dipolar couplings of spin labeled molecules like proteins, RNA or DNA³. Due to the single frequency setup, there is no sensitivity lost like in PELDOR with two frequency settings, which limits the excitation of the EPR spectrum and...

The study of metabolic changes (metabolomics) is a rapidly growing field of research. Starting with the detection of potential disease markers in the 1970's, applications reach from toxicological and / or pharmacological studies to the field of food analysis. The metabolome is the last step in the so-called omics cascade where it reacts most sensitive to changes in genome, transcriptome,...

In different crystalline silicophosphates like SiP₂O₇ or Si₅P₆O₂₅ the silicon is coordinated to six oxygen atoms.^[1] Of particular interest is the role of silicon pyrophosphate phases. Materials with such [SiO₆] moieties can be obtained by various reaction routes. We established a “water-free” synthetic route based on...

CLIP-COSY^[1] experiment, providing high quality homonuclear correlation spectrum with clean in-phase multiplets, accelerates the assignment of J-coupled proton spin network and so, the structure elucidation of small and medium-sized molecules. Further resolution enhancement and, hence, simplification of spectra can be obtained by implementing the recently introduced PSYCHE...

The hyperpolarization of nuclear spins using para-hydrogen (pH₂) is a fascinating technique that allows increasing spin polarization and, as a result, the magnetic resonance signal by several orders of magnitude. Entirely new applications become available. Signal Amplification By Reversible Exchange (SABRE) is a relatively new method that is based on the reversible exchange of a...

Due to the recent development of the microwave (MW) technique, Electron Paramagnetic Resonance (EPR) spectroscopy is currently making a significant progress in the sub-THz frequency range. For example, experiments at frequencies above 0.2 THz were recently performed employing rapid scan methodology to record EPR spectra [1]. In these High Frequency Rapid Scan (HFRS)-EPR experiments the...

Intrinsically disordered proteins (IDPs) as well as intrinsically disordered regions (IDRs) of complex protein machineries have recently been recognized as key players in many cellular functions. NMR represents a unique tool to access atomic resolution structural and dynamic information on highly flexible IDPs/IDRs. Improvements in instrumental sensitivity made heteronuclear direct detection...

Singlet state NMR spectroscopy is an emerging field, dealing with techniques for efficient storage of spin hyperpolarization and investigation of various slow processes. To increase the singlet-order (SO) lifetimes, special molecules have been designed, some having a SO lifetime of 1.5 hours in room temperature solutions. At the same time, to repeat the experiment with extended SO lifetimes...

Singlet-state NMR is an important emerging methodology for overcoming limitations imposed by finite nuclear spin relaxation times. Specifically, one can exploit advantages of long-lived spin states (LLSs) and long-lived coherences (LLCs). LLSs exist when the symmetry of the static and fluctuating Hamiltonian coincide; consequently, such states become immune to particular kinds of relaxation....

Recently, site-specific dynamic nuclear polarization (DNP) has shifted into the scientific focus, with the aim to restrict hyperpolarizing to a specific region of interest, or even extract distance information by directly analyzing DNP parameters, such as enhancement factor and polarization build-up rate.[1]
In this work we present recent results of site-directed spin labeling on a protein to...

The Growth Hormone Secretagogue Receptor (GHSR) belongs to the family of G protein-coupled receptors. It is a seven transmembrane (TM) domain protein which undergoes a conformational change to an active state upon ligand binding and is part of the signal transduction pathways into the cells. It represents an attractive target due to its role in food intake. Besides the knowledge of its...

NMR spectroscopy is a quick and efficient tool for diagnosis and follow up of many inborn errors of metabolism. In many suspicious cases, particularly in countries where only a few inborn errors are included in national screenings, NMR may provide the first indication for a rare metabolic disease.
We report on a case of a five months old girl diagnosed with galactosemia which was followed up...

Several theoretical studies using molecular dynamics MD simulations showed an enhancement of water dynamics inside hydrophobic channels and a peak of the liquid self-diffusion coefficient is reported at certain carbon nanotube sizes. The studies have shown that this enhancement depends on the size of the hydrophobic nanochannels. However, experimental evidence of this dependence is lacking so...

Ring flips of phenylalanine and tyrosine are a hallmark of protein dynamics. They report on transient breathing motions of proteins. In addition, flip rates also depend on stabilizing interactions in the ground state, like aromatic stacking or cation-pi interaction. So far, experimental studies of ring flips have almost exclusively been performed on aromatic rings without stabilizing...

Curcumin is a hydrophobic Active Pharmaceutical Ingredient with anti-oxidant and anti-inflammatory properties. To overcome challenges in its oral delivery, a novel drug delivery system has been developed [1]. It consists of solid lipid nanoparticles (SLN) embedded in a porous silica matrix (SBA-15). The material is structured in a network of meso-pores, filled with surfactant micelles, linking...

In the past few years, the interest in research of inorganic/organic hybrid materials has increased tremendously. Especially, novel nanoparticles based on inorganic/organic hybridmaterials have been designed for applications ranging from heterogeneous catalysts for environmentally friendly chemical transformations, to materials with optical or sensoric properties.
The crucial step for tuning...

The aggregation of hyperphosphorylated tau into amyloid fibrils is closely linked to the progression of Alzheimer’s disease. To gain insight into the link between amyloid structure and disease, the three-dimensional structure of tau fibrils has been studied using solid-state NMR (ssNMR) and cryogenic electron microscopy (cryo-EM). In addition, cryo-EM structures of tau fibrils purified from...

Misfolded β-amyloid (Aβ) is associated with Alzheimer’s disease (AD) and the most abundant species (isoforms) in brains are 40-residue Aβ40 and 42-residue Aβ42. As those Aβs have different properties, despite similarities in their amino acid sequences, aggregation kinetics and structures of both Aβ40 and Aβ42 fibrils have been studied separately to investigate the mechanism of AD. However,...

Anhydrous proton-conducting polymers available above 100 °C have been widely developed for their applications in solid electrolyte fuel cells. Several proton-conducting polymer-imidazole composites have been proposed. In these composites, imidazole (Im) molecules are intercalated into a polymer and provide a proton conduction path. When proton conductivity of the polymer-Im composites is...

Typical colloidal nanoparticle can be viewed as a nanocrystal-ligands complex with an inorganic core bonded with a monolayer of organic ligands. Surface ligands are an essential part of nanocrystal-ligands complexes and dramatically affect their properties, such as stability, biological compatibility and solution processability. Solid-state nuclear magnetic resonance (SSNMR) is one of the best...

Lipidic cubic phases, which form spontaneously via the self-assembly of certain lipids in an aqueous environment, are highly prospective nanomaterials with applications in membrane protein X-ray crystallography and drug delivery. We report 1H-15N heteronuclear single/multiple quantum coherence (HSQC, HMQC) spectra of 15N enriched proteins encapsulated in lipidic bicontinuous cubic phases...

Ionic liquids (ILs) are nowadays well known as alternative media for organic, catalytic and electrochemical applications¹. Nonetheless, traditional ILs tend to incorporate imidazolium or pyridinium cations which have high toxicity, low biodegradability and high cost². For that reason, ILs synthesized from bio-organic molecules have gained considerable interest and their...

Perfluorinated sulfonic acid (PFSA) membranes are polymers known for their high proton conductivity and mechanical stability. The benchmark material is Nafion, which is often described as a long side-chain (LSC) polymer with two fluoroether groups. However, these fluoroether groups suffer from several drawbacks in fuel cell application. Therefore, a new type of PFSA membrane was introduced,...

We have optimized the transfer of magnetization between ¹H that can be utilized in indirect DNP (Dynamic Nuclear Polarization) experiments. Three different sequences for such a transfer exist presently: CPMAS, PRESTO (Phase-shifted Recoupling Effects a Smooth Transfer of Order) and D-RINEPT-$SR4^2_1$ (Dipolar-based Refocused-INEPT with $SR4^2_1$ recoupling). CPMAS is not a robust...

Spin noise and maser emissions in NMR are two phenomena, which are linked, if not caused by radiation damping. [1-3] Our research group has been investigating spin noise in imaging and spectroscopy for some time. [4,5] NMR maser phenomena have been observed initially for hyper-polarized spin ensembles [6] but recently have also been reported in samples with inverted thermal polarization...

Design of new bio-nano hybrid systems incorporating cellular membranes calls for understanding and accounting for the influence of nanosupport and nanoconfinement on the structure and properties of lipid bilayer, lipid-solid and lipid-protein interfaces. Further progress in this field requires development of spectroscopic methods capable of characterizing nanoparticle interfaces and,...

The energy splitting of the spin states of high-spin (S > 1) solid-state defects due to magnetic anisotropy is one of the key issues for their application in future quantum technologies. This splitting, addressable by electron paramagnetic resonance (EPR), sensitively depends on the intrinsic properties of the defect and appears in the absence of external fields, i.e. in the zero-field....