Partial purification and characterization of a thermostable alkaline protease from Lactobacillus brevis

ABSTRACT

Aims: The research was done to study the partial purification and characterization of thermostable alkaline protease from Lactobacillus brevis. Methodology and Results: The enzyme was purified in a two-step procedure involving ammonium sulphate precipitation and Sephadex G-150 gel permeation chromatography. The protease was purified 8.04 fold with a yield of approximately 30% after purification with Sephadex G-150 column. It has a relative molecular weight of 33.2 kDa and optimally active at a temperature of 60 oC and pH 9.0. The maximum velocity Vmax and Michaelis constant Km of the protease produced during the hydrolysis of casein were 66.66 U/mg protein and 3.33 mg/ml. It was strongly activated by Ca2+ and ethylene diamine tetra acetic acid (EDTA), mildly inhibited by Na+, K+, Mg2+ and Fe2+ and strongly inhibited by Cu2+ and Hg2+. The ability of the enzyme to improve the cleansing power of various detergents was also studied. Conclusion, significance and impact of study The findings in this study suggest that the protease is a suitable candidate for detergent formulation and biotechnological applications.