Purification and characterization of extracellular alkaline protease from Streptomyces sp. LCJ12A isolated from Pichavaram mangroves

ABSTRACT

Extracellular protease from culture supernatants of Streptomyces sp. LCJ12A was purified and characterized in thisstudy. The collected supernatant of Streptomyces sp. LCJ12A was purified by ammonium sulfate precipitation anddiethylaminoethyl cellulose chromatography. The molecular weight of the enzyme was 20.1 kDa. Sodium dodecylsulfate-polyacrylamide gel electrophoresis was used to determine the molecular weight of the enzyme. The culture filtrate,partially purified enzyme, and ammonium sulfate precipitate displayed catalysis and stability over pH 3–11.5 and showedoptimal activity at pH 10. The culture filtrate, ammonium sulfate precipitate, and partially purified enzyme were goodbetween 30 and 40°C and the optimum temperature was 35°C. The purified protease exhibited high catalytic activityand stability under different pH and temperature. The partially purified protease from Streptomyces sp. LCJ12A showeda substantial relative activity of 78% with bovine serum albumin (BSA), 43% with gelatin, and 96% relative activitywith casein. Lineweaver–Burk plot was used to calculate the Km and Vmax values for the partially purified protease.The Km values of Streptomyces sp. LCJ12A were 73.5 mM for casein, 44.54 mM for BSA, and 43.45 mM for gelatin.The Vmax values were 500 mM min−1 for casein, 303.03 mM min−1 for BSA, and 270.27 mM min−1 for gelatin fromStreptomyces sp. LCJ12A. The statistical analysis confirmed that compared to the other substrates, casein was significant.