The use of the electronegativity equalization principle to study charge distributions in enzymes: application to dipeptides

Abstract

The aim of this paper is the introduction of the use of the electronegativity equalization principle to study charge distribution in enzymes. This method holds an economic way to study these large systems. The principle is at first, used here to study charge distributions in simple peptides having the β-sheet structure and a β-sheet heptapeptide sequence from the serine protease subtilisin BPN. Two different approximations to the electronegativity of a group in a molecule were used to obtain the amino acid group charges which were then compared with ab initio calculated charges: the simple Huheey approximation and a version including external potential perturbation effects. It turns out that the simple Huheey equation, which can readily be used for larger systems, yields the best results and that a more refined and time consuming treatment of the external potential will be necessary for further improvement of the results.