Extraction, Purification and Characterization of Fish Chymotrypsin: A Review

Problem statement: Solid fish waste is generated from the unwanted parts of fish including heads, tails, fins, frames, offal (guts, kidney and liver) and skin. It accounts for up to 80% of material from production of surimi, 66% from production of fillet and 27% from production of headed and gutted fish. Currently, fish wastes are disposed off in land-based waste disposal systems or at sea generating toxic by-products during the decomposition process. However, fish processing waste can be used to produce commercially valuable by-products, such as chymotrypsin. Approach: A comperehensive review of the literature on the extraction, purification and characeterization of fish chymotrypsin was performed. Results: Chymotrypsin is an endopeptidase secreted by the pancreatic tissues of vertebrates and invertebrates. It has 3 different structures (chymotrypsin A, B and C) varying slightly in solubility, electrophoretic mobility, isoelectric point and cleavage specificity. Only chymotrypsin A and B are found in fish. Compared with mammal chymotrypsin, fish chymotrypsins have similar amino acid composition and molecular weights. Fish chymotrypsins have higher specific activity, especially those from cold-water fish, and low pH and temperature tolerance. The factors affecting the concentration and activity of chymotrypsin in fish are water temperature, fish species, fish age, fish weight and starvation. Chymotrypsin has application in various industries including the food industry, leather production industry chemical industry and medical industry. Conclusion: Extraction techniques for chymotrypsin include: ultra-filtration, ammonium sulphate fractionation precipitation or water-in-oil microemulsions. Purification can be carried out using re-crystallization and gel-filtration, ion-exchange and hydrophobic interaction chromatography. Further studies should focus on the optimization of purifiying chymotrypsin from fish processing wastes.