シロサケ幽門垂に存在する2種の主要アニオニックトリプシンの性質(シロサケ幽門垂トリプシンに関する研究-2-)

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Two anionic trypsins designated as DI-1 and DII-2 which were two main components in trypsins purified from the pyloric caeca of chum salmon Oncorhyncus keta had a molecular weight of 24, 000 and 238, 000, S0, 20, W of 3.27 and 3.00, respectively, and similar acid compositons to those of mammalian trypsins. Their optimum pH of hydrolysis for N-tosyl-L-arginine methyl ester (TAME) were found to be 7.5-8.0 and 8.0, and for casein were 10-11 and over 11, respectively. Both enzymes specificaly hydrolyzed arginine and lysine methyl ester, and reacted with N-tosyl-L-lysine chloromethyl ketone (TLCK) and diisopropylfluorophosphate (DEP) according to a first order reaction mechanism at a rate constant of 2.1-5.8×10-8sec-1, and with soybean trypsin inhibitor (STT) and chicken ovomucoid (COM) at a molar ratio of about 1:1. The activities of both enzymes were not effected by any divalent cations, and were unstable at pH below 5 and stable at pH 7-9. This stability at pH 7-9 was increased in the presence of low concentration of Ca2+ (5 mM) and decreased in the presence of EDTA. DI-1 treated completly with EDTA lost about 50% of original activity and markedly decreased stability at pH 7-9. Lost activity was recovered to original activity in the presence of Ca2+ and other divalent cations, however, stability was not. These results in the EDTA treatment suggest that DI-1 may hold Ca2+ so tightly that it is unremovable from enzyme by a dialysis and treatment with EDTA for a short time to maintain activity and stability of enzyme at pH 7-9.
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シロサケ幽門垂に存在する2種の主要アニオニックトリプシンの性質(シロサケ幽門垂トリプシンに関する研究-2-)

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