PREDICTIONS OF PROTEIN BACKBONE BOND DISTANCES AND ANGLES FROM FIRST PRINCIPLES

A procedure is described, based on a spline-function representation of ab initio peptide conformational geometry maps, that allows one to predict backbone bond distances and angles of proteins as functions of the peptide phi(N-C-alpha)/psi(C-alpha-C') torsions with an accuracy comparable to that of high-resolution protein crystallography. For example, for the move than 40 residues of crambin, the rms deviation between predicted and crystallographic values of N-C-alpha-C' is 1.9 degrees for the 1.5 Angstrom resolution structure and 1.7 degrees for the 0.83 Angstrom resolution structure, compared with angle variations of > 10 degrees. Accurate information on protein backbone geometries is important for establishing dictionaries of flexible geometry functions for use in empirical peptide and protein modeling. (C) 1995 John Wiley & Sons, Inc.