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‐NMecand TAME, but not BAEE and BAPNA. Optimum Z‐Phe‐Arg‐NMec hydrolyzing activity was shown at pH 7.4, 40 to 50 °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 and B are most likely tryptic serine type proteinases.