Kinetic parameters of hydrolysis of peptide and protein substrates by psychrophilic endopeptidases from hepatopancreas of the king crab Paralithodes camtschaticus (PC), in particular, by trypsin, collagenolytic protease, and metalloprotease, were measured at different temperatures. The PC trypsin was shown to hydrolyze Bz-Arg-pNA in the temperature range studied (4-37 degrees C) 19 times more effectively than bovine trypsin. The rate constants of hydrolysis of Glp-Ala-Ala-Leu-pNA by the PC collagenolytic protease increased approximately by one order of magnitude along with temperature decrease, while Km decreased by 3.5 times. The effective values of Km for the hydrolysis of azocasein by the metalloprotease insignificantly depend on temperature. We proposed that electrostatic interactions of negative charges around the cavity of active site are critical for the effective hydrolysis of substrates by endopeptidases of the PC hepatopancreas.