Purification and properties of trypsin-like enzymes from the starfish Lysastrosoma anthosticta

Abstract

Two trypsin-like enzymes, designated as A and B, were isolated from the starfish Lysastrosoma anthosticta. The homogeneity of both enzymes was confirmed by disc electrophoresis in polyacrylamide gel and by N-terminal analysis. The minimum molecular weight of both enzymes was 25 000, this having been determined by gel filtration on Sephadex G-100 and electrophoresis in polyacrylamide gel in the presence of 1% sodium dodecylsulphate. The enzymes were inhibited with di-isopropylphosphorofluoridate, N- tosyl- l-lysine chloromethyl ketone and a soybean trypsin inhibitor. The pH optimum of the hydrolysis of N-benzoylarginine- p-nitroanilide is almost the same for both enzymes. The isoelectric points for proteinases A and B are at pH 6.5 and 4.5, respectively. Both enzymes proved to be unstable at pH below 5.0. Hydrolysis of the insulin B-chain showed both enzymes to have a specificity similar to that of bovine pancreatic trypsin.