魚類の糖代謝酵素系に関する研究-3-肝臓のグルコ-ス-6-りん酸脱水素酵素とグルコ-ス脱水素酵素の特性

概要

論文の詳細を見る
One of the two enzymes isolated from the liver of rainbow trout, yellowtail and grass carp was highly specific for G6P and NADP, for which Km values were 41-85 and 15-20 μM, respectively. The maximum activity was found at pH 8.5, any it was activated by Mg2+, inhibited by dehydroisoandrosterone, and not affected by anions. On the basis of such findings, the enzyme was classified as G6P dehydrogenase Another enzyme catalyzed the oxidation of glucose as well as G6P at almos the same rate, and Km values for these substrates were 26-35 mM and 16-24 μM respectively. The G6P oxidation by this enzyme, for which the optimum pH wa 10-10.5, was inhibited by Mg2+ and not affected by ATP. From these results, the enzyme was considered to be glucose (hexose phosphate) dehydrogenase. On the other hand, the only enzyme isolated from the liver of carp and eel showed typical G6P dehydrogenase activity and also much less glucose dehydrogenase activity. Therefore, the enzyme seemed to be G6P dehydrogenase having a wide specificity. The possible role of these three dehydrogenases in sugar metabolism in fish was discussed.
日本水産學會の論文