Abstract:In this study, the characteristics of an extracellular protease produced by Halogranum rubrum RO2-11 were studied. Skimmed milk powder medium was used to confirm extracellular protease production, while enzyme activity was determined by Folin-Phenol method. The results showed that Halogranum rubrum RO2-11 produced an extracellular protease with a certain tolerance to high concentration of NaCl. The optimum temperature for enzymatic reaction was 50 ℃. The temperature tolerance of the enzyme decreased at temperatures exceeding 60 ℃. The optimum pH for enzymatic reaction was 8.0. The enzyme showed high activity and stability between pH values of 8.0 and 11.0, demonstrating that the enzyme was an alkaline protease. The enzyme was activated by Ca2+ but was inhibited by Mn2+ and Cu2+. EDTA had a strong inhibitive effect on the protease. However, isopropanol, DTNB (a mercapto reactant) and PMSF (a serine inhibitor) had little influence on the activity of the enzyme, which showed that the enzyme might be a metalloprotease without a mercapto group and tolerant towards organic solvent to a certain extent.
