[nmrlearner]

Spinning faster: protein NMR at MAS frequencies up to 126Â*kHz

Abstract

We report linewidth and proton T1, T1Ï? and T2â?² relaxation data of the model protein ubiquitin acquired at MAS frequencies up to 126Â*kHz. We find a predominantly linear improvement in linewidths and coherence decay times of protons with increasing spinning frequency in the range from 93 to 126Â*kHz. We further attempt to gain insight into the different contributions to the linewidth at fast MAS using site-specific analysis of proton relaxation parameters and present bulk relaxation times as a function of the MAS frequency. For microcrystalline fully-protonated ubiquitin, inhomogeneous contributions are only a minor part of the proton linewidth, and at 126Â*kHz MAS coherent effects are still dominating. We furthermore present site-specific proton relaxation rate constants during a spinlock at 126Â*kHz MAS, as well as MAS-dependent bulk T1Ï? (1HN).



Source: Journal of Biomolecular NMR