Dynamic properties of proteins from NMR spectroscopy.

Two-dimensional proton-detected heteronuclear nuclear magnetic resonance spectroscopy has been used to measure 13C and 15N spin-relaxation rate constants for several proteins. Generalized order parameters and effective internal correlation times have been calculated from the relaxation data to characterize intramolecular motions that are more rapid than overall rotational diffusion. These studies provide detailed descriptions of the magnitudes and timescales of fluctuations in protein molecules.