Locating hydrogen atoms in single crystal and uniaxially aligned amino acids by solid-state NMR

摘要

We demonstrate a novel method to locate hydrogen atoms in amino acids, which involves measuring the C alpha H alpha bond vector geometry through orientationally dependent dipolar coupling frequencies measured by Lee-Goldburg cross polarization (LGCP). A 2D LGCP experiment is used to measure the polar angle of the C alpha H alpha bond vector in a single crystal of the model compound L-alanine. It is also demonstrated that by coupling the (C alpha H alpha)-C-13-H-1 LGCP experiment to a (C alpha N)-C-13-N-15 REDOR experiment, one can determine the complete three-dimensional geometry of the C alpha H alpha and C alpha N vectors in a single crystal. These measurements allow for location of hydrogen atoms in crystalline biological macromolecules. (c) 2007 Published by Elsevier Inc.