posted on 2021-12-27, 13:05authored byKai Xue, Evgeny Nimerovsky, Kumar A. Tekwani Movellan, Stefan Becker, Loren B. Andreas
Protein torsion angles
define the backbone secondary structure
of proteins. Magic-angle spinning (MAS) NMR methods using carbon detection
have been developed to measure torsion angles by determining the relative
orientation between two anisotropic interactionsdipolar coupling
or chemical shift anisotropy. Here we report a new proton-detection
based method to determine the backbone torsion angle by recoupling
NH and CH dipolar couplings within the HCANH pulse sequence, for protonated
or partly deuterated samples. We demonstrate the efficiency and precision
of the method with microcrystalline chicken α spectrin SH3 protein
and the influenza A matrix 2 (M2) membrane protein, using 55 or 90
kHz MAS. For M2, pseudo-4D data detect a turn between transmembrane
and amphipathic helices.