マダコ肝臓のたん白分解酵素の二,三の性質について

概要

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Some properties of the partially purified, proteolytic enzyme preparation from the liver of octopus, Octopus vulgaris CUVIER, were investigated. 1. The optimun pH for casein hydrolysis was in two pH ranges of 2.0-3.0 and 5.5-6.0. 2. The enzyme activity on casein at pH 2.5 and that at pH 6.0 were the most stable in the pH range 4.0-5.5 in both cases and when heated for 30 minutes at pH 5.0 the former was stable up to 50°C, while the latter was stable up to 45°C. 3. The effect of bivalent metallic ions and NaCN on casein hydrolysis at pH 2.5 was negligible, while the enzyme action was accelerated by cysteine and ascorbic acid. On the other hand, the hydrolysis of casein at pH 6.0 was strongly accelerated not only by cysteine and ascorbic acid but also by NaCN, while a very weak inhibition with metallic ions such as Mn2+, Cu2+ and Zn2+ was observed. 4. The enzyme preparation hydrolyzed carbobenzoxy-L-glutamyl-L-tyrosine at pH 5.0 and also deamidated benzoyl-L-argininamide and glycyl-L-phenylalaninamide at pH 5.0 in the presence of cysteine. 5. The above results suggest that the octopus liver contains at least two distinct proteolytic enzymes, the major part of which consists of cathepsin-like enzymes.
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