INEPT-Based Separated-Local-Field NMR Spectroscopy: An Unique Approach to Elucidate Side Chain Dynamics of Membrane-Associated Proteins

摘要

Despite recent advances in NMR approaches for structural biology, determination of membrane protein dynamics in its native environment continues to be a monumental challenge as most NMR structural studies of membrane proteins are commonly carried out in either micelles or in vesicle systems under frozen conditions. To overcome this difficulty, we propose a solid-state NMR technique that allows for the determination of side chain dynamics from membrane proteins in lipid bilayers. This new technique, namely dipolar enhanced polarization transfer (DREPT), allows for a wide range of dipolar couplings to be encoded, providing high resolution and sensitivity for systems that undergo motional averaging such as that of amino acid side chains. NMR observables such as dipolar couplings and chemical shift anisotropy, which are highly sensitive to molecular motions, provide a direct way of probing protein dynamics over a wide range of timescales. Therefore, using an appropriate model it is possible to determine side chain dynamics that can provide additional information on the topology and function of a membrane protein in its native environment.