Studies on purification and characterization of a protease from a marine bacterium, Pseudomons sp. 7~11

A protease from the culture supernatant of marine bacteria Pseudomonas sp. 7~11 was discovered. One component of the protease was purified to homogeneity by ammonium sulfate precipitation, dialysis, ion exchange chromatography. The specific activity of the enzyme was raised from 19.46U·mg -1 to 13953115U·mg -1 ,which was 717.02 times that of the culture supernatant with a yield of 1.24%.The molecular mass of purified enzyme was estimated to be 3000Da about by SDS PAGE. The optimum temperature for the activity was observed to be 45℃ using casein as substrate.The optimum pH for activity the enzyme was 8.0 and it was stable between pH6～7 and below 50℃.The activity of the enzyme was inhibited by EDTA and IAA strongly. But was not inhibited by PMSF. the enzyme was inhibited Mn 2+ , Hg 2+ , Fe 2+ , Zn 2+ , Cu 2+ ,Pb 2+ and SDS. The inactivity of the enzyme with EDTA could be recovered partially by Mg 2+ .while Ca 2+ , Mg 2+ and (NH 4) 2SO 4 was activator for the activity of the enzyme. The activity of the enzyme was fairly stable in the presence of ethanol and urea, and was resistant to Tween 20.