Proteolytic activity of preparations of crystallized ribonuclease

Abstract

Crystalline prepns. of ribonuclease invariably possessed proteolytic activity, which varied in amt. in different prepns. The pH zones of proteolytic and ribonuclease activities were somewhat d ifferent. Between pH 4 and 4.5 only the ribonuclease activity, though far from its opt., was demonstrable. By heating at. pH 7 - 7.5 under specified conditions, the proteolytic activity was greatly reduced or destroyed, leaving between 30-80% of the original ribonuclease activity. Ribonuclease was attacked by pepsin, chymotrypsin, and the proteolytic enzyme of crystalline prepns. of ribonuclease.