~ 1252 ~ Journal of Entomology and Zoology Studies 2020; 8(1): 1252-1258 E-ISSN: 2320-7078 P-ISSN: 2349-6800 JEZS 2020; 8(1): 1252-1258 © 2020 JEZS Received: 20-11-2019 Accepted: 24-12-2019 Biswajit Mohanty School of Fisheries, Centurion University of Technology & Management, Odisha, India RK Majumdar College of Fisheries, Central Agricultural University (I), Tripura, India Corresponding Author: Biswajit Mohanty School of Fisheries, Centurion University of Technology & Management, Odisha, India Partial purification and characterization of digestive acidic and alkaline proteases from the visceral waste of grass carp, Ctenopharyngodon idella (Valenciennes, 1844) Biswajit Mohanty and RK Majumdar Abstract Acidic and alkaline proteases from visceral waste of Ctenopharyngodon idella (Valenciennes, 1844) were isolated, partially purified by ammonium sulphate precipisstation followed by dialysis, their kinetics and characteristics studied. The crude enzyme was partially purified and its molecular weight was studied. The enzyme showed highest activity and purification-fold when precipitated at 40–60% ammonium sulfate. The purification fold increased from 1.23 to 2.49 and 1.17 to 1.51 in acidic and alkaline protease respectively along the purification steps. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) showed a molecular weight 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 3 and 10, at 40 °C and 60 °C respectively. The acidic and alkaline protease activity was decreased by 40% and 60%, when incubated at 90 °C for 30 min. Degree of hydrolysis (DH) of the proteases on muscle protein increased with increase of enzyme concentrations. The study showed that proteases from Grass carp visceral waste of could find use in applications where maximum activity at moderate temperature is desired. Keywords: Ctenopharyngodon idella, acidic proteases, alkaline proteases, enzyme purification fold 1. Introduction Proteases constitute one of the most valuable groups of industrial enzymes used in the world today and it has multiple applications in the food industry [2] . The Protease enzymes are chiefly derived from plant, animal and microbial sources, whereas their counterparts, derived from marine and other aquatic sources, have not been extensively used. In recent years, additional applications of proteases in the seafood industry have been emerged. These include the selective removal of skin, hydrolysis of membranes and other supportive tissue that envelope roe, roe seeks and other tissues, and recovery of pigments and flavour extract [3] . There have been relatively few attempts to use fish proteases as industrial processing aids. Fish are poikilothermic and vary considerably in their feeding habits and temperature preferences, and so it is expected that their digestive enzymes will also exhibit diversity [4] . Amongst the hydrolytic enzymes, proteases represent an important class of industrial enzymes; have been employed in different applications, mostly in food, detergent, textile, leather and pharmaceutics as well as in waste management and bioremediation process [4, 5] . However, proteases require their purification and characterization before any application. Proteases contribute about 60% of the world's total enzyme production and used worldwide [6] . Presently, most of the proteolytic enzymes are extracted from bacteria, and relatively few attempts have been made on the application of fish proteases as industrial processing aids. Usually, the fishery by-products are typically used as feeds and fertilizers. Recently, interest has grown to search high-value functional bio-molecules from the fishery wastes, notably enzymes. Nevertheless, several researchers investigated proteases from the visceral wastes from marine fish [7, 8] . But characterization of fish proteases especially from the visceral wastes of freshwater fish is seldom reported. The grass carp Ctenopharyngodon idella (Valenciennes, 1844) [1] is the species of fish with the largest reported production in aquaculture globally, over five million tonnes per year. It is a large herbivorous freshwater fish species of the family Cyprinidae native to eastern Asia. A huge quantity of visceral wastes is generated in the retail fish markets due to pre-processing. Such biological wastes, if not utilized otherwise, would pose a problem of their disposal and