Cathepsin characterization from crude extract of yellow pike (Congresox talabon)

摘要

Fish is a highly perishable food due to internal and external factors. Cathepsin, a proteolytic enzyme available in animal tissues, affects quality deterioration of fish by hydrolizing muscle proteins. Yellow pike fish have an edible portion that is relatively high but has not been used optimally. The aim of the study was to extract the cathepsin enzyme from yellow pike meat. The method used extraction, characterization, and precipitation of ammonium sulfate (NH_4)_2SO_4 fraction at concentrations of 40-50% to 70-80%. The extraction results showed the crude extract activity of cathepsin from yellow pike fish which was 0.19 U/mL. The optimum activity of the cathepsin enzyme at a pH 5 (0.24 U/mL), temperature of 50°C (0.10 U/mL) and metal ions increased cathepsin activity, one of which was CuCl_2 increased cathepsin activity to 0.92 U/mL and FeCl_3 increased activity to 1.41 U/mL. The best precipitate at 40-50% ammonium sulfate concentration with specific activity 1.15 U/mg.