Characterization of a Purified Thermostable Protease from Hyperthermophilic Bacillus Strain HUTBS71

The extracellular thermostable protease was purified in a 3-steps procedure involving ammonium sulfate fractionation, Sephadex G-100 gel permeation and DEAE-ion exchange chromatography. The enzyme was purified 59-fold with 1.8% yield. The purified enzyme consists of a single polypeptide with molecular mass of 49 kDa. The protease activity was observed at pH range from 7.0 to 9.2 with an optimum pH 7.8. While the activity was observed at temperature ranges from 50oC to 80oC with 65oC as optimum. The present enzyme was also stable after incubation at 50oC and 60oC for 2 h retained 84% of its original activity. The activation energy of denaturation of purified enzyme was 24.8 kJ mol. The half-lives of the enzyme at 60oC, 70oC and 80oC were estimated to be 8, 6 and 5 h, respectively. The activity of the enzyme was enhanced in the presence of 5 mM Mn, Ca and Na; not affected or slightly inhibited by Fe, Co, and Zn but inhibited remarkably by EDTA, Cu and Cd.