Nuclear magnetic resonance studies of internal mobility in globular proteins

This paper presents a survey of the use of high resolution n.m.r. for studies of the internal mobility of globular protein structures. In a first part n.m.r. manifestations of internal motions are described. This includes discussion of the exchange of internal labile protons with the solvent, flipping motions of aromatic rings, and effects of internal mobility on 13C relaxation parameters and on vicinal spin-spin coupling constants. A second part summarizes the results of a n.m.r. characterization of the molecular dynamics of the basic pancreatic trypsin inhibitor, which demonstrates that the information content of n.m.r. data on protein mobility depends critically on the availability of individual resonance assignments. This is followed up in a third part, which briefly recounts a recently proposed, systematic approach by two-dimensional n.m.r. spectroscopy for obtaining individual assignments of proton resonances in proteins.