[Purification and characterization of extracellular halophilic protease from haloarchaea Natrinema sp. R6-5].

A halophilic extracellular protease from a halophilic archaea Natrinema sp. R6-5 was purified to SDS-PAGE homogeneity using bacitracin-Sepharose 4B chromatography. A molecular mass of the purified protease subunit was 62KD determined by SDS-PAGE. The protease activity was inhibited by phenylmethylsulfonyl fluoride (PMSF), suggesting that the protease belong to serine protease. The protease exhibited optimum NaCl concentration is 3 mol/L. At the 3 mol/L NaCl concentration, the optimum temperature and the optimum pH were 45 degrees C and 8.0. The protease could keep high activity and stability in high salt environment and had potential application value.