Influence of local interactions on protein structure. II. Conformational energy studies of N‐acetyl‐N′‐methylamides of Ala‐X and X‐Ala dipeptides

Abstract

Conformational energy calculations using an empirical conformational energy program for peptides (ECEPP) were carried out on 17 N‐acetyl‐N′‐methylamides of Ala‐X and X‐Ala dipeptides, Where X = Ala, Asn, Asp, Gly, Phe, Ser, Tyr, Val, and Pro. Each dipeptide was found to have many low‐energly minima, some of which corresponded to bend structures. The stability of bends was found to depend on the amino acid composition and sequence, with the Ala‐X dipeptide generally favoring bends more than the X‐Ala dipeptide for a particular X. In bends and nonbends alike, intraresidue interactions dominate over interresidue interactions in determining conformational propeties. The calcutions were shown to be in good agreement with available experimental data.