Two Kinds of Neutral Serine Proteinases in Salted Muscle of Anchovy, Engraulis japonica

Abstract

Two kinds of proteinases, type-I and type-II, were purified or partially purified from salted muscle of anchovy, Engraulis japonica. Mol. wts. of type-I and type-II proteinases were estimated to 25, 000 and 37, 000, respectively, on electrophoretic analysis. Both proteinases strongly hydrolyzed synthetic tri or tetrapeptide substrates specific to trypsin, α-thrombin, and an activated protein C, while they hardly hydrolyzed Arg-MCA and benzoyl Arg-MCA derivatives. The proteinases were inhibited by common trypsin inhibitors. Optimal pH for the proteinase activities were pH 6.8 (type-I) and pH 7.0 to 7.5 (type-II), and the proteinases showed the highest activities at 45°C (type-I) and 50°C (type-II). The N-terminaI amino acid sequence of type-I proteinase, ¹I-²V-³G-⁴G··· (29 residues were identified), was significantly similar to sequences of trypsins and tryptases. Based on these findings, both proteinases were presumed to be kinds of tryptases in E. japonica muscle.