Quantitative Measurement Of Exchange Dynamics In Proteins Via C-13 Relaxation Dispersion Of (Chd2)-C-13-Labeled Samples

Methyl groups have emerged as powerful probes of protein dynamics with timescales from picoseconds to seconds. Typically, studies involving high molecular weight complexes exploit (CH3)-C-13- or (CHD2)-C-13-labeling in otherwise highly deuterated proteins. The (CHD2)-C-13 label offers the unique advantage of providing C-13, H-1 and H-2 spin probes, however a disadvantage has been the lack of an experiment to record C-13 Carr-Purcell-Meiboom-Gill relaxation dispersion that monitors millisecond time-scale dynamics, implicated in a wide range of biological processes. Herein we develop an experiment that eliminates artifacts that would normally result from the scalar coupling between C-13 and H-2 spins that has limited applications in the past. The utility of the approach is established with a number of applications, including measurement of ms dynamics of a disease mutant of a 320 kDa p97 complex.