Intracellular Protease from Streptococcus durans

An intracellular protease from Streptococcus durans was isolated and partially purified and characterized. A 67-fold purification was obtained with retention of 53% of the original activity. Purification was complicated by the presence of nucleic acids which could not be removed without loss of proteolytic activity. Ribonuclease inactivated the protease, but attempts to reactivate the protease by adding ribonucleic acid extracted from ~q. durans were unsuccessful. Disc electrophoresis of the enzyme in polyacrylamide gel showed one protein zone with an adjoining nucleic acid zone.