Propeptin, a New Inhibitor of Prolyl Endopeptidase Produced by Microbispora : II. Determination of Chemical Structure

The structure of propeptin, a new inhibitor of prolyl endopeptidase isolated from Microbispora sp. SNA-115, was determined. FAB/MS, Edman degradation and amino acid analysis revealed propeptin to be a cyclic polypeptide consisting of 19 common L-amino acids. By FAB/MS and protein chemical methods, the primary sequence of propeptin was determined to be Gly 1 -Tyr-Pro-Trp-Trp-Asp-Tyr-Arg-Asp 9 -Leu-Phe-Gly-Gly-His-Thr-Phe-lle-Ser-Pro 19 , which cyclizes between the β-carboxyl group of Asp 9 and the α-amino group of Gly 1 .