THE C-13 CHEMICAL-SHIFT INDEX - A SIMPLE METHOD FOR THE IDENTIFICATION OF PROTEIN SECONDARY STRUCTURE USING C-13 CHEMICAL-SHIFT DATA

A simple technique for identifying protein secondary structures throug h the analysis of backbone C-13 chemical shifts is described. It is ba sed on the Chemical-Shift Index [Wishart et al. (1992) Biochemistry, 3 1, 1647-165 1 ] which was originally developed for the analysis of H-1 alpha chemical shifts. By extending the Chemical-Shift Index to includ e C-13alpha, C-13beta and carbonyl C-13 chemical shifts, it is now pos sible to use four independent chemical-shift measurements to identify and locate protein secondary structures. It is shown that by combining both H-1 and C-13 chemical-shift indices to produce a 'consensus' est imate of secondary structure, it is possible to achieve a predictive a ccuracy in excess of 92%. This suggests that the secondary structure o f peptides and proteins can be accurately obtained from H-1 and C-13 c hemical shifts, without recourse to NOE measurements.