Abstract
Protease was obtained from the culture filtrate of Aeromonas hydrophila by ion-exchange chromatography and gel filtration. It gave a single band on disc electrophoresis and a single precipitin line on immunoelectrophoresis. The molecular weight was estimated to be 57, 500 by SDS-polyacrylamide electrophoresis, but it was estimated to be 33, 000 by gel filtration. The enzyme was stable at pH 6 to 10, and the optimum pH for the activity was 7.5 to 8.5. The enzyme was stable at 50°C, but 30% of the activity was lost by heating for 1 h at 60°C. Chelating agents, Ni2+, Cu2+. Cd2+, and Hg2+ inhibited the enzyme activity. Carp injected with 200μg of the protease per 100g body weight died, showing extensive hemorrhages in the abdominal cavity. Hemorrhages and necrosis were observed in the guinea-pig skin upon intracutaneous injection of 3.13μg protease.
