Partial purification and characterization of pseudoalteromonas piscicida jcr 18 protease

Proteases able to function in a broad range of alkaline pH, temperature, salts, solvents and detergents are the most preferred from an industrial point of view. An extracellular alkaline protease with thermos table properties was isolated from a marine bacterium Pseudoalteromonas piscicida strain JCR 18 obtained from seawater, off the coast of Marina, Chennai. The enzyme was isolated and partially purified using gel chromatography and SDS-PAGE and was seen to be a monomer having a molecular weight of 30kDa. The specific activity was seen to be 172.4 U/mg at 27-fold purification and with an yield of 3%. It exhibited optimum activity at a temperature of 50°C and pH 9. It was inhibited by PMSF and DFP showing it to be a serine protease. The activity was only slightly enhanced by metal ions like Ca2+, Mg2+, and Mn2+showing that it is cofactor-independent. Increased activity was seen with casein as substrate. This protease with its high specific activity, alkaline pH range, thermo stability and reduced cofactor requirement would be best suited for detergents, gelatinization of x-rays and dehairing applications in leather industries.