Rapid evaluation of molecular electrostatic potential maps for amino acids,peptides, and proteins by empirical functions

A simple method for evaluating the molecular electrostatic potential (MEP) map without self-consistent field molecular orbital (SCF-MO) calculation is extended, and the parameters for amino acids, peptides, and proteins are determined. In this method, the electrostatic potentials due to electrons in the valence shells are calculated by a set of simple empirical functions at various origins, and those due to the core electrons and nuclei by point charge approximation. For application of the method to amino acids, peptides, and proteins, the functions for the σ and π bonds and lone-pair electrons involved in these species were determined, and the MEP maps calculated by the empirical functions were compared with those calculated by an ab initio method. It is shown that the method reproduces correctly the shape of ab initio MEP map even for the repulsive MEP region. The method is shown to be very useful for rapid evaluation of reliable MEPs for large biological molecules. © 1996 by John Wiley & Sons, Inc.