Off-resonance rotating-frame amide proton spin relaxation experiments measuring microsecond chemical exchange in proteins
NMR spin relaxation in the rotating frame (R-1 rho) is a unique method for atomic-resolution characterization of conformational ( chemical) exchange processes occurring on the microsecond time scale. Here, we use amide H-1 off-resonance R-1 rho relaxation experiments to determine exchange parameters for processes that are significantly faster than those that can be probed using N-15 or C-13 relaxa