Abstract:The effects of reaction temperature, pH, and metal ions (Zn2+, Mg2+, Cu2+, Fe3+, Al3+, and Ca2+) on the protease activity of crude enzymes of Antarctic krill were studied, and the inhibitory effects of phenylmethanesulfonyl fluoride (PMSF), EDTA∙2Na, iodoacetamide (IAM), and toluenesulfonyl- phenylalanine chloromethyl ketone (TPCK) on protease activity also were investigated. The experimental results indicated the optimum reaction temperature of the protease in the crude enzyme of Antarctic krill was 40℃, and the optimum pH was 8.0; when the metal ion concentration was 0.5 mmol/L, the inhibitory rates of Zn2+, Mg2+, Cu2+, Fe3+, and Al3+ on the protease activity of Antarctic krill were 55.02%, 55.02%, 35.39%, 20.67%, and 41.12% respectively, while protease activity increased in the presence of Ca2+. The protease activity was significantly inhibited by PMSF and EDTA∙2Na. When the concentration of PMSF was 8.0 mmol/L, the inhibition rate was 60%; when the concentration of EDTA∙2Na was 0.6 mmol/L, the inhibition rate was 86.67%. IAM had a certain inhibitory effect at low concentrations, while TPCK showed no inhibitory effect. With the increase in temperature, the inhibitory effect of EDTA∙2Na on enzyme activity was gradually increased in the temperature range of 5–30℃. This study clarified the factors affecting the enzyme activity of Antarctic krill crude enzyme and developed an inhibitor of protease activity thereof, which provides the basic theoretical data for the development and utilization of Antarctic krill in the food industry.
