Conformational studies on alamethicin

Abstract

A conformational analysis has been carried out for the cyclic peptide antibiotic alamethicin. Unlikely structures were first eliminated by constructing van der Waals' energy maps for near‐neighbor contacts and using these maps to generate forty complete alamethicin structures free of steric overlaps. The energies of the forty conformations were minimized; optimizing all dihedral angles first in sets and then simultaneously, to give a family of five low‐energy structures. In the conformation of lowest energy three of the seven α‐amino isobutyric acid residues occur in a six‐residue α‐helix and three at the two chain reversals. Judged by the change in conformational energy as a function of the..