The relationship between peptide plane rotation (PPR) and similar conformations

Currently, several energy functions and conformational search methods have been developed that are based on the observed distribution of phi and psi a ngles in protein structures. The definition of phi and psi angles is direct ly related to the orientation of the peptide plane (CA-CO-NH-CA). Starting from one conformation and rotating a single peptide plane, the angles psi f or one residue and phi for the consecutive residue that are linked by the p eptide plane, display a continuous range of values within one global confor mation. When peptide plane rotation is analyzed in several different confor mations generated from a restricted conformation database, a large number o f these conformations are related, Based on these observations, a new simpl ified all-atom representation for protein folding simulations is presented where only one torsion angle variable is required for each residue, The und erlying theme of this article is that conformational search methods using p hi and psi torsion space, search through many redundant conformations. Thes e conformations are related by anticorrelated torsion changes of peptide pl ane rotations. (C) 1999 John Wiley & Sons, Inc.