Solid-State NMR Measurements of Asymmetric Dipolar Couplings Provide Insight into Protein Side-Chain Motion

摘要

Understanding conformational flexibility is of critical importance for understanding protein function, folding, and interactions with other proteins and ligands. NMR spectroscopy is an important tool for such investigations in solution and increasingly also in the solid state since it allows site-resolved studies of dynamic processes. An experimental characterization of all motional modes of a protein is a great challenge and simplified models are necessary. In NMR studies of dynamics, motional amplitudes are generally expressed in terms of a single order parameter, discarding the details of the motion, such as the motional asymmetry. Herein, we show a significant extension of this description, by detecting asymmetric motion of side chains in a protein in the solid state.