摘要：

The proteolytic enzymes in the muscle fluid of Pacific whiting(Merluccius productus) were studied and compared to those found in musclefluid of true cod (Gadus macrocephalus). Preliminary studies indicatedthree pH optima of activity for whiting, pH 3.5-3.9, 4.3-4.6 and 7.1-7.2.Only two pH optima were found for the proteolytic activity of true cod,pH 3.2-3.6 and 7.7-8.0.The sarcoplasmic fluid of whiting and cod muscle was studied inmore detail. For both whiting and cod, no hydrolysis of the substrateshippuryl-L-phenylalanine, hippuryl-L-arginine, α-N-benzoyl-D,L-argininep-nitroanilide (BAPA), or toluene sulfonyl arginine methyl ester (TAMA)at neutral pH's could be detected, indicating the absence of trypsin andcarboxypeptidases A and B. Neither whiting nor cod contained elastaseand only whiting was shown to have activity similar to that of cathepsinB. True cod was found to contain higher chymotrypsin activity thanwhiting at pH 7.15 using the substrate glutaryl-L-phenylalaninep-nitroanilide. Hydrolysis of the substrate glutaryl-L-phenylalanineβ-naphthylamide (Gly-Phe-2-naphthylamide) from pH 5 to 8 occurred to agreater extent in Pacific whiting than in true cod.Various inhibitors and activators were used to characterize theenzymes in whiting and cod muscle hydrolyzing the substrates GPNA andGly-Phe-2-naphthylamide. The responses to the chemicals were comparedwith the effects reported in the literature on the hydrolysis of thesubstrates by enzymes found in other animal sources.

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