Dynamics of uniformly labelled solid proteins between 100 and 300 K: A 2D 2H-13C MAS NMR approach

We describe a H-2 based MAS nuclear magnetic resonance (NMR) method to obtain site-specific molecular dynamics of biomolecules. The method utilizes the use of deuterium nucleus as a spin label that is proven to be very useful in dynamics studies of solid biological and functional materials. The aim is to understand overall characteristics of protein backbone and side-chain motions for CD3, CD2 and CD groups, in terms of timescale, type and activation energy of the underlying processes. Variable temperature two-dimensional (2D) H-2-C-13 correlation MAS NMR spectra were recorded for the uniformly H-2,C-13,N-15 labelled Alanine and microcrystalline SH3 at a broad temperature range, from 320 K down to 100 K. First, the deuterium quadrupolar-coupling constant from specific D-C sites is obtained with the 2D experiment by utilizing carbon chemical shifts. Second, the static quadrupolar patterns are obtained at 100 K. Third, variable temperature approach enabled the observation of quadrupolar pattern over different motional regimes; slow, intermediate and fast. And finally, the apparent activation energies for C-D sites are determined and compared, by evaluating the temperature induced signal intensities. This information led to the determination of the dynamic processes for different D-C sites at a broad range of temperature and motional timescales. This is a first representation of 2D H-2-C-13 MAS NMR approach applied to fully isotope labelled deuterated protein covering 220 K temperature range. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

A H-2 based MAS NMR method was used to study the molecular dynamics of biomolecules, revealing the characteristics of protein backbone and side-chain motions at different temperatures. The research provided insights into the activation energies and motional timescales of various D-C sites in proteins using a 2D H-2-C-13 MAS NMR approach.