Studies on the conformation of amino acids. II. Potential energy of conformations of glycine, alanine and aminobutyric acid

Abstract

In this paper, the results of the potential energy calculations on the conformations of some amino acids are given. The non-bonded, electrostatic, and torsional contributions to the total energy of the molecule were calculated using appropriate functions and their role in predicting the conformation of amino acids is discussed. It is shown that electrostatic interaction between the amino group and the carboxyl group is mainly responsible for the plane of the carboxyl group to be coplanar with the plane through N, C^α, and C¹atoms. It is also shown that the presence of a δ-atom in position II necessiates a large deviation from the coplanarity between the carboxyl plane and the N, Cα, C plane. The results indicate that the backbone conformations of all the amino acids are nearly the same and could be shown to be the same as those of glycine and alanine. Also, the theoretically predicted conformations about the C^α-C^β bond in aminobutyric acid could explain the observed γ-atom positions in all the amino acids.