Abstract: The effect of endogenous enzymes on the autolysis of sea cucumber (Stichopus japonicas) guts was studied by addition of various protease inhibitors. The autolysis was evaluated by the release of trichloroacetic acid (TCA)-soluble oligopeptides and reducing sugar, and detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results indicated that different inhibitors, including pepsin inhibitor, trypsin inhibitor, serine protease inhibitor, amylase inhibitor and β-1,3-glucanase inhibitor showed inhibitory effects on the autolysis of S. japonicus guts in a certain range of concentration. The serine protease inhibitor N-tosyl-L-phenylalaninyl-chloromethyl ketone (TPCK) showed relatively higher inhibitory effect than the other inhibitors. These results suggest endogenous enzymes, including pepsin, trypsin, serine proteases, amylase and β-1,3-glucanase, may be involved in the autolysis of S. japonicus guts.

Key words: Stichopus japonicus, guts, autolysis, endogenous enzymes, serine proteases