Detailed analysis of protein structure and function by NMR spectroscopy: survey of resonance assignments

Techniques are now available for making extensive assignments in NMR spectra of proteins of moderate size (molecular weight 20,000 or less). Such assignments provide the first step for experiments designed to extract the full complement of NMR parameters for each group in a protein. The stage is set for exciting research scenarios in protein chemistry involving, for example, the determination of hydrogen exchange kinetics at all exchangeable positions whose half times are on the order of 100 ms (277) or longer than a few minutes (316, 569, 570); the characterization of intermediates in protein folding pathways (318); measurement of the distribution of internal motions within a protein molecule (573); a detailed description of the biophysical consequences of single amino acid replacements in small proteins (387); elucidation of the mechanisms of conformational transitions in proteins; and multiparametric characterization of the parts of an enzyme that participate in catalytic mechanisms. Small proteins for which extensive 1H NMR assignments have been made include lysozyme, several cytochromes, ferredoxins, myelin basic proteins, PTI and related proteinase inhibitors, proteinase inhibitors from seminal plasma and avian eggs, apamin, and several snake venom neurotoxins. (References are given in Table 1).