Purification and characterization of proteinase from Atlantic menhaden muscle

Two proteinases (A and B) were isolated from Atlantic menhaden muscle with molecular weights of 112,000 and 90,500 daltons, respectively. Proteinase B had higher activity than A for protein substrates except casein; proteinase B had no caseinolytic activity. Both proteinases hydrolyzed synthetic substrates such as Z-Phe-Arg-NMec and TAME, but not BABE and BAPNA. Optimum Z-Phe-Arg-NMec hydrolyzing activity was shown at pH 7.4, 40 to 50 degrees C for both proteinases A and B, Activities of A and B in the presence of 3.0% NaCl were reduced to 71.2% and 62.2%, respectively. Both proteinases were inhibited by 1 mM TLCK, 1 mM benzamidine, 1% egg white, and 1% bovine plasma hydrolysate. Proteinases A acid B are most likely tryptic serine type proteinases.