Alkaline Serine Protease from Marine Bacillus Flexus APCMST-RS2P: Purification and Characterization
Thirumalai Maruthiah, Palanichamy Esakkiraj, Grasian Immanuel and Arunachalam Palavesam
Protease enzyme from estuarine sediment bacterium Bacillus flexus was purified by using two steps such as ammonium sulphate precipitation (37.25 yield and 2.75 fold purification) and sephadex G-75 gel filtration chromatography (9.83% enzyme yield and 10.62 fold purification). Molecular weight of the purified protease was detected as 44.3 kDa. The maximum protease activity was observed at pH 8.0 and this enzyme was stable in the pH range of 8-9 after 1.5 h of incubation. Also at 40°C the protease activity was maximum and it was stable between the temperatures range of 40 to 50°C after 1.5 h of incubation. This enzyme is slightly halophilic and the highest activity was observed in 0.5 M NaCl concentration. Further the tested surfactants were found to enhance the protease activity; also this enzyme persists its activity in the presence of SDS (5mM). The effect of metal ions showed that, mercuric chloride and zinc chloride completely inhibited the protease activity and the optimum activity was noticed in medium added with barium chloride and magnesium chloride. The serine protease inhibitor was found to inhibit 90% activity and hence it was identified as serine protease type. This enzyme effectively hydrolyzed casein when compared to BSA and gelatin.
Alkaline serine protease, Bacillus flexus, non ionic and commercial detergents
Marine Biotechnology Laboratory, Centre for Marine Science and Technology, Manonmaniam Sundaranar University, Rajakkamangalam, 629 502 Kanyakumari District, Tamilnadu, India.