Date of Award

6-1990

Document Type

Union College Only

Degree Name

Bachelor of Science

Department

Chemistry

Language

English

Abstract

By virtue of employing a modified version of a popular program for the calculation of polypeptide conformational energies, the lowest energy conformation of the tyrocidine molecule is being sought. This antibiotic molecule, a cyclic decapeptide, invited study due to its role in the process of bacterial sporulation in the Bacillus Brevis ATCC 818!2 strain. In the process of performing this investigation, lists of monopeptide lowest energy conformations, as determined by x-ray crystallographic studies, were combined to yield all possible combinations of half of the polypeptide chain. Beginning with a dipeptide, the conformations of lowest energy were calculated within a 'local-minimum' range; hereafter, a tripeptide was created from this dipeptide, as specified above, and similar calculations were performed. Finally, the tripeptide and a dipeptide calculated previously were then combined to yield the pentapeptide PHE-DPHE-ASN-GLN-TYR, which then underwent minimizing calculations to yield a set of 11 conformations, one of which possessed a probability of existence of 51.8%. The resulting lowest energy conformations of the pentapeptide will be joined with a pentapeptide from the lowest energy minima of gramicidin-S, PRO-DPHE-LEU-ORN-VAL, to yield the tyrocidine conformation.

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