A Simple Approach to Analyzing Protein Side-Chain Dynamics fromC NMR Relaxation Data

A simple approach to deriving motional dynamics information of protein and peptide side chains by using¹³C NMR relaxation data is presented. By using linear approximation of internal rotational correlation functions, simple equations for relating side-chain 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-coupled¹³C NMR relaxation measurements allow detailed motional information to be obtained.