南極オキアミのプロテアーゼ活性と自己消化

概要

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The protease activity of an aqueous extract prepared from Antarctic kirll, Euphausia superba, was examined, mainly at 37°C, with casein, hemoglobin and the specific trypsin substrate benzoyl-arginine-β-naphthylamine as substrate. The pH-activity curve for hydrolyzing the typsin substrate had a peak near pH 7 and was similar to those for hydrolyzing casein and hemoglobin. However, most of the krill protease activity was neither trypsin nor trypsinlike enzyme. On the body weight basis, the krill protease activity was comparable to that of a shrimp, Sergestes lucens, analyzed for reference and was not as high as had been expected. This was also found to be same even at low temperatures such as 4°C. Since most of the protease activity was detected in the cephalothorax of the body, this was considered to be visceral enzymes. From the above result, it is concluded that the breakable krill body could be chiefly attributable to the weak physical structure of cephalothorax, so once the viscera is destroyed physically during the handling, visceral enzymes bring about additional digestive breakdowns of the organs themselves and of the surrounding tissues.
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