25-30 August 2019
Henry Ford Building
Europe/Berlin timezone

Ever faster magic-angle spinning – 150 kHz solid-state NMR spectroscopy

Not scheduled
4h
Harnack House and Henry Ford Building

Harnack House and Henry Ford Building

Board: 412
Poster Posters

Speaker

Mr Maarten Schledorn (ETH Zürich)

Description

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 width in deuterated and fully back-protonated as well as in fully protonated proteins has been reduced to a degree which makes proton-detected solid-state NMR an attractive and accessible alternative with the positive side effect that much smaller sample amounts are needed for a typical application.

The development of proton detection in solid-state NMR has come with an increase in mass sensitivity of two orders of magnitude. Consequently, one might ask if we can expect to benefit from a continued investment in faster spinning. To address this question, MAS up to 150 kHz is used to investigate a complex of archaeal RNA polymerase subunits 4 and 7, in which the Rpo4 unit with 107 amino-acid residues is at natural isotopic abundance while the 187 residues of Rpo7 are 13C-15N-labeled.

Using a rotor with an outer diameter of 0.51 mm and a uniformly 13C- and 15N-labeled sample content of approximately 100 µg, we observe a linewidth improvement of a factor 1.3 for 150 kHz compared to 100 kHz. This compensates (to ~90 %) for a factor ~1.5 of signal reduction due to the smaller rotor size necessary for faster spinning, considering the fact that the dimension of the detection coil is decreased as well. We show linear improvement of coherence lifetimes in a range of 100 to 150 kHz MAS and demonstrate that the technical challenges of investigating proteins at this MAS frequency can be overcome, concluding that continued efforts toward faster spinning are thus meaningful and timely.

Primary authors

Mr Maarten Schledorn (ETH Zürich) Dr Anahit Torosyan (ETH Zurich) Mr Alexander A. Malär (ETH Zürich) Mr Andres Oss (Tallinn University of Technology) Ms Mai-Liis Org (Tallinn University of Technology) Dr Susanne Penzel (ETH Zurich) Dr Daniel Klose (ETH Zurich) Prof. Ago Samoson (Tallinn University of Technology) Dr Anja Böckmann (Molecular Microbiology and Structural Biochemistry - CNRS) Prof. Beat H. Meier (ETH Zurich)

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