Partial Characterization of an Acidic Protease from Rhizopus stolonifer RN-11

Abstract

The present study characterises an acidic protease purified from the Rhizopus stolonifer strain, RN-11. The acidic protease with a 70 kDa molecular weight, was stable within pH 2-4 at temperatures 40-50°C. The temperature and pH value conducive to optimal catalytic activity were pH 2.5 and 50°C, respectively. Treatment with 5 mmol metal ions showed that the acidic protease was activated by Na + , K + , Mn 2+ , Cu 2+ and Ca 2+ , inhibited by Zn 2+ , Li 2+ and Fe 2+ , and unaffected by Mg 2+ . It was proposed that the studied acidic protease might represent a previously uncharacterised type of acidic protease produced by the Rhizopus stolonifer RN-11 strain.