Methyl groups as probes of supra-molecular structure, dynamics and function.

The development of new protein labeling strategies, along with optimized experiments that exploit the label, have significantly impacted on the types of biochemical problems that can now be addressed by solution NMR spectroscopy. Here we describe how methyl labeling of key residues in a highly deuterated protein background has facilitated studies of the structure, dynamics and interactions of supra-molecular particles. The methyl-labeling approach is briefly reviewed, followed by a summary of applications to three different molecular machines so as to illustrate the types of questions that can now be addressed. Areas where future innovations will lead to yet further improvements are highlighted as well.