A comparison of the N-terminal sequence of the leech Theromyzon tessulatum angiotensin converting-like enzyme with forms of vertebrate angiotensin converting enzymes.

摘要

This paper reports the purification of an angiotensing-converting like enzyme (ACE) of ca. 120 kDa from extracts of head membranes of the leech Theromyzon tessulatum. After solubilization with Triton X-114, the ACE-like enzyme contained in the detergent-poor fraction was separated using five steps of purification including gel permeation and anion exchange chromatographies followed by reverse-phase HPLC. The first 23 amino acid residues of the N-terminal part (GLDPELSPGCFSADEAGAQLFAE) of the purified S-pyridylethylated leech ACE established by automated Edman degradation revealed ca. 87% sequence identity with the N-terminal sequence of the guinea pig ACE. This enzyme cleaves the hyppuryl-His-Leu substrate with a specific activity of 5600 nmol hyppurate min-1 mg protein-1. Hydrolysis of this substrate by ACE-like enzyme is inhibited at 80% by 10 microM captopril or 10 microM lisinopril (IC50 of 200 nM and 50 nM, respectively). This enzyme is close in sequence and in activity to single domain vertebrateACE. This is the first N-terminal sequence of an ACE-like enzyme determined in invertebrates.