Purification and characterization of a high molecular weight serine protease from Microbacterium paraoxydans sp....

Alkaline proteases from microbial sources have been found suitable for diverse industrial applications, with serine proteases being the most common enzymes used in the detergent industry. In the present study, we have purified and characterized an extracellular alkaline serine protease from Microbacterium paraoxydans sp. SKS10. The protease was purified using ammonium sulfate precipitation followed by different chromatography techniques (fold purification 6.919). K_m and V_max for the protease were determined to be 0.183 mg/mL and 4.904 U/mL, respectively. This enzyme is a thermostable high molecular weight (∼109.4 kDa) protease which has maximal activity at 60°C, and above pH 10. Inhibitor assays revealed the enzyme to be a serine protease whose activity increased by 2.5-fold in the presence of EDTA. This enzyme remained active in the presence of various metal salts and organic solvents and was compatible with commercially available laundry detergents highlighting its potential for use in the detergent industry.