Paecilopeptin, a New Cathepsin S Inhibitor Produced by Paecilomyces carneus

Abstract

Paecilopeptin, a novel cathepsin S inhibitor, was produced and isolated from the culture supernatant of the fungal strain, Paecilomyces carneus. A spectroscopic analysis revealed the planar structure of paecilopeptin to be acetyl-Leu-Val-CHO. The stereochemistry of the constituent amino acids was analysed by chiral HPLC after oxidation and 6N HCl hydrolysis of paecilopeptin. The total synthesis of paecilopeptin was completed in six steps. Paecilopeptin inhibited human cathepsin S with an IC₅₀ value of 2.1 nM in vitro.

• cathepsin S
• enzyme inhibitor
• Paecilomyces carneus
• structural elucidation
• peptide