Purification of Alkaline Serine Protease From Local Bacillus subtilis M33 by Two Steps: a Novel Organic Solvent and Detergent Tolerant Enzyme

Abstract

Alkaline proteases are important from an industrial perspective due to their wide scaleapplications and obtained from different sources. In this study, an alkaline protease from a newlyisolated Bacillus subtilis M33 was purified by ammonium sulfate precipitation and DEAEcellulose anion exchange chromatography with 38.66% yield and 15.50 fold. The results ofsodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) and gel chromatographyindicate that the molecular weight of the purified enzyme is 39 kDa. The enzyme present pH andtemperature optimum of 10.0 and 55°C The purified enzyme has been found to maintain stabilityover a wide range (pH 8.0-11.0) for 7 days.. Phenylmethyl sulfonyl fluoride (PMSF) which is aspecific inhibitor completely inhibited the enzyme activity. However, the increased activity of theenzyme in the presence of 2-mercaptoethanol and dithiothreitol indicates that the enzyme is athiol-dependent serine protease. The enzyme retained its stability with laboratory bleaches(H2O2), surfactants (Tween 80, Triton X-100, SDS) and organic solvents such as ethanol,toluene, propanol. The enzymatic behavior of the purified enzyme in the presence of somecommercial detergents was also evaluated. The two important Michaelis Menten parameters Kmand Vm were calculated 0.706 mg/ml, 3000 μM.min-1 respectively.