Characterization of digestive acidic and alkaline proteolytic enzyme (proteases) from the visceral wastes of Chinese major carp, Cyprinus carpio (Linnaeus, 1758)

Abstract

Acidic and alkaline proteases from visceral waste of Cyprinus carpio (Linnaeus, 1758) were extracted, partially purified by ammonium sulphate precipitation followed by dialysis. Their enzyme kinetics and characteristics were studied. The purification fold increased from 1.39 to 2.24 and 1.46 to 2.17 in acidic and alkaline protease respectively along the purification steps. The molecular weights were found in the range of 15-35 kDa and 25-63 kDa respectively in acidic and alkaline proteases. The pH and temperature optima for acidic and alkaline proteases were 4 and 11, and 40°C and 70°C respectively. The protease activity was found decreased by 40 and 60% when incubated at 90°C for 30 min. Both the proteases showed a declining activity of more than 50% at NaCl concentration of 0.5%. Degree of hydrolysis of the proteases on muscle protein increased with increase of enzyme contents. Both soybean trypsin inhibitor and EDTA exhibited high percentage of inhibition when proteases were incubated with 50 mM of both. Enzyme activators like NaCl and CaCl2 (10mM) increased the activity of acidic protease by 18.56% and 29.11% respectively. The study showed that proteases from Common carp visceral waste could find use in Industrial applications.