ISOLATION AND PARTIAL CHARACTERIZATION OF A HEAT-STABLE EXTRACELLULARPROTEASE FROM PSEUDOMONAS SP AFT-36

Pseudomonas sp. AFT-36, a psychrotrophic organism of dairy origin, pro duced an extracellular heat stable protease enzyme. This protease was purified to homogeneity from a cell free broth culture by sequential u se of ammonium sulphate precipitation, acetone fractionation and gel f ilteration through Sephadex G-100. The purified enzyme was thermostabl e and retained about 25% activity even after treatment at 75-degrees-C for 30 min in buffer. The enzyme was inhibited by heavy metal ions an d also by metal chelating agents as EDTA and 1,10-phenanthroline. It h ad a molecular weight of 39 KDa and k(m) value of 2.5 mg/ml for whole casein.