A simple approach to analyzing protein side-chain dynamics from 13C NMR relaxation data

A simple approach to deriving motional dynamics information of protein and peptide side chains by using C-13 NMR relaxation data is presented. By using linear approximation of internal rotational correlation functions, simple equations for relating sidechain conformation, bond rotational amplitudes, and rotational correlation coefficients with different NMR relaxation parameters have been obtained. Auto-and cross-correlation spectral densities are considered, and it is shown that proton-coupled C-13 NMR relaxation measurements allow detailed motional information to be obtained. (C) 1998 Academic Press.