水産動物のglucose-6-phosphataseに関する研究-I : 魚類の肝臓glucose-6-phosphataseの諸性質

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The enzymatic properties of hepatic glucose-6-phosphatase in fishes were investigated, and the results obtained were as follows:1. Glucose-6-phosphatase, catalyzing specific hydrolysis of glucose-6-phosphate, was found in the liver of flying fish and yellow-tail. Its optimum pH and temperature lay at pH 6.0 and 40°C, respectively.2. As a result of study on intracellular distribution of the enzyme, the highest specific activity was found in “Heavy microsome fraction”, in which 35% of the total activity was found.3. The enzyme activity was rapidly decreased by preincubation at pH 4.0 ?? 5.5, but relatively stable at pH 7.5.4. Apparent Michaelis constant was 3.6×10-3M.5. The enzyme activity was scarcely inhibited by glucose and inorganic phosphate at the low concentration, but considerably at the high concentration of glucose. Other hexoses and pentoses did not inhibit so much as glucose.6. The enzyme activity was strongly inhibited by Mo6+, Hg++, and Cu++ at 10-2 ?? 10-3M, but neither stimulated nor inhibited by Ca++ and Mg++.