Cross examination of the conformational spaces of a set of peptide chains: Study of oligopeptidase action

Abstract

A conformational search was carried out for five opioid peptide homologues and for angiotensin II. Density of states versus energy plots were obtained for each peptide, and the occurrence of common main-chain conformations was investigated by searching homologies between strings of four, five, and six contiguous main-chain amino acid residues rotamers. the results were compared to rates of hydrolysis by endooligopeptidase (EOP) 24.15, known for its specificity for substrate conformations. A catalytic assay of the hydrolysis of angiotensin II was also performed. the two best substrates of EOP 24.15 were found to share unique main-chain conformations and the two worst substrates of EOP 24.15 were found to be nonstructurally homologous to each other and the remaining peptide chains. the conformational search is compared to previous experimental and theoretical results. (C) 1996 John Wiley & Sons, Inc.INST BUTANTAN, LAB BIOQUIM & BIOFIS, BR-05503900 São Paulo, BRAZILUniversidade Federal de São Paulo, DEPT BIOFIS, São Paulo, BRAZILUniversidade Federal de São Paulo, DEPT BIOFIS, São Paulo, BRAZILWeb of Scienc