Isolation of Polypeptide Inhibitor of Phospholipase A from Cobra Venom

Abstract

A polypeptide inhibitor of phospholipase A has been isolated from cobra venom (Naja naja). It is a basic protein with an isoelectric point above pH 8.6. The molecular weight is 5000. The inhibitor has been shown to form an inactive complex with the enzyme in the ratio of 1:1. The complex having a molecular weight of approximately 15000 was isolated using Sephadex G‐100. The complex disintegrated into the component units in starch gel electrophoresis suggesting the involvement of electrostatic bonds in its formation. It was observed that the basic proteins salmine, polylysine and cobra cytotoxin did not inhibit phospholipase A. The inhibitor did not combine with some of the basic proteins isolated from cobra venom. The inhibitor was specific for the phospholipase A and apparently interacts with groups which are involved in its catalytic activity. Copyright © 1970, Wiley Blackwell. All rights reserved