title: Off-resonance TROSY (R1 rho - R1) for quantitation of fast exchange processes in large proteins.
abstract: Current solution NMR experiments for characterizing conformational exchange processes in large proteins are limited to exchange rates ca. 500-3000 s-1. A TROSY-based constant relaxation time (R1rho - R1) experiment is designed to extend this capability to measure motion with rates up to 105 s-1 in large macromolecules. The experiment combines off-resonance spin-lock rf fields, which provide access to the faster time-scale dynamics, with TROSY coherence selection, which extends the molecular-weight range available for study. When implemented on the 53-kDa dimeric enzyme triosephosphate isomerase, the experiment yielded substantial gains in signal-to-noise (up to 60%) over current experiments at modest static magnetic fields (14.1 T). The TROSY (R1rho - R1) experiment should therefore be of general utility for investigation of fast conformational exchange events in large proteins.
mesh_terms: D007700:Kinetics; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*
chemical_list: D011506:Proteins