Characteristics of trypsin from the pyloric ceca of walleye pollock (Theragra chalcogramma)

Trypsin was purified from the pyloric ceca of walleye pollock (Theragra chalcogramma) by gel filtration on Sephacryl S-200 and Sephadex G-50. The final enzyme preparation was nearly homogeneous in sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) and the molecular mass of the enzyme was estimated to be 24 kDa by SDS–PAGE. Trypsin activity was effectively inhibited by serine protease inhibitors, such as soybean trypsin inhibitor and TLCK. Trypsin had maximal activities at around pH 8.0 and 50 °C for the hydrolysis of Nα-p-tosyl-l-arginine methyl ester hydrochloride. Trypsin was unstable above 30 °C and below pH 5.0, and was stabilized by calcium ions. Walleye pollock trypsin was more thermally unstable than trypsin from the Temperate Zone fish and Tropical Zone fish. The N-terminal amino acid sequence of the trypsin, IVGGYECTKHSQAHQVSLNS, was found, and the sequential identity between the walleye pollock trypsin and Frigid Zone fish trypsin was higher (85–100%) than with Temperate Zone fish trypsin (75–90%), Tropical Zone fish trypsin (75–85%), or mammalian trypsin (60–65%).