Pumpkin (Cucurbita sp.) seed globulin VI. Protcolytic activities appearing in germinating cotyledons

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N-α-benzoyl D,L-arginine p-nitroanilide (BAPA) , leucine p-nitroanilide (LPA) and casein hydrolytic activities were assayed in germinating cotyledons. BAPA hydrolytic activity was not detected in dry seeds, but increased rapidly from 1 to 4 days of germination and then decreased. LPA and casein hydrolytic activities were detected in dry seeds and increased from 2 to 4 days. Casein hydrolytic activity decreased faster than the other two activities. BAPA hydrolytic enzyme was partially purified. It was inhibited by p-chloromercuribenzoate and activated by β-mercaptoethanol and dithiothreitol, but was not affected by EDTA, phenylmethylsulfonyl fluoride, pumpkin trypsin inhibitor and several divalent cations. It had no ability to hydrolyze globulin or the γ' chain to produce F_<αβ> or smaller polypeptides, respectively, which was referred to as proteolytic activity I in the preceding paper (14), but released small peptides and amino acids from the δ chain and F_<αβ>. However, it was different from proteolytic enzyme II which was present in dry seeds and inhibited by EDTA (14). Pumpkin trypsin inhibitor was purified. Its molecular weight was estimated to be 10,500 by gel filtration. It did not inhibit the BAPA hydrolytic enzyme. Both proteolytic activities I and II were also not. reduced by the inhibitor (14). The inhibitory activity decreased gradually during germination.
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