CROSS EXAMINATION OF THE CONFORMATIONAL SPACES OF A SET OF PEPTIDE CHAINS - STUDY OF OLIGOPEPTIDASE ACTION

A conformational search was carried out for five opioid peptide homolo gues and for angiotensin II. Density of states versus energy plots wer e obtained for each peptide, and the occurrence of common main-chain c onformations was investigated by searching homologies between strings of four, five, and six contiguous main-chain amino acid residues rotam ers. The results were compared to rates of hydrolysis by endooligopept idase (EOP) 24.15, known for its specificity for substrate conformatio ns. A catalytic assay of the hydrolysis of angiotensin II was also per formed. The two best substrates of EOP 24.15 were found to share uniqu e main-chain conformations and the two worst substrates of EOP 24.15 w ere found to be nonstructurally homologous to each other and the remai ning peptide chains. The conformational search is compared to previous experimental and theoretical results. (C) 1996 John Wiley & Sons, Inc .