Purification and partial characterization of serine protease from thermostable alkalophilic <Emphasis Type="Italic">Bacillus laterosporus</Emphasis>-AK1

An extracellular thermostable alkaline protease isolated from Bacillus laterosporus-AK1 was purified by sephadex G-200 gel filtration and DEAE cellulose ion-exchange chromatography techniques. The purified protease showed a maximum relative activity of 100% on casein substrate and appeared as a single band on SDS-PAGE with the molecular mass of 86.29 kDa. The protease was purified to 11.1-folds with a yield of 34.3%. Gelatin zymogram also revealed a clear hydrolytic zone due to proteolytic activity, which corresponded to the band obtained with SDS-PAGE. The protease enzyme had on optimum pH of 9.0 and exhibited highest activity at 75°C. The enzyme activity was highly susceptible to the specific serine protease inhibitor PMSF, suggesting the presence of serine residues at the active sites. Enzyme activity strongly enhanced by the metal ions Ca²⁺ and Mg²⁺ and this enzyme compatible with aril detergent stability retained 75% even 1-h incubation. The purified protease remove bloodstain completely when used with Wheel detergent.