Ghosh B, De B P, Biswas B B
Arch Biochem Biophys. 1984 Jan;228(1):309-19. doi: 10.1016/0003-9861(84)90072-9.
A novel enzyme, myo-inositol-1-phosphate dehydrogenase, which catalyzes the conversion of myo-inositol 1-phosphate to ribulose 5-phosphate has been purified 84-fold from mung bean seedling employing several common techniques. The molecular weight of this purified enzyme has been recorded as 88,500 by Sephadex G-200 column chromatography, and in sodium dodecyl sulfate-polyacrylamide gel electrophoresis one protein band containing three subunits of Mr 32,000 each was discernible. Km values for NAD+ and myo-inositol 1-phosphate have been recorded as 2.8 X 10(-4) and 5.0 X 10(-4) M, respectively. Production of NADH in myo-inositol-1-phosphate dehydrogenase reaction has also been evidenced by measurement of NADH fluorescence. Dehydrogenation and decarboxylation of myo-inositol 1-phosphate are mediated by the same enzyme. In fact, the rate of dehydrogenation corroborates with that of decarboxylation. Stoichiometry of this reaction suggests that for the production of 1 mol of ribulose 5-phosphate 2 mol of NAD+ are reduced.
一种新型酶——肌醇-1-磷酸脱氢酶，可催化肌醇1-磷酸转化为5-磷酸核酮糖，利用几种常见技术从绿豆幼苗中纯化了84倍。通过葡聚糖G-200柱层析法测得该纯化酶的分子量为88,500，在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳中可辨别出一条含有三个亚基、每个亚基分子量为32,000的蛋白带。NAD⁺和肌醇1-磷酸的Km值分别记录为2.8×10⁻⁴和5.0×10⁻⁴ M。通过测量NADH荧光也证实了肌醇-1-磷酸脱氢酶反应中NADH的产生。肌醇1-磷酸的脱氢和脱羧由同一种酶介导。实际上，脱氢速率与脱羧速率相符。该反应的化学计量表明，为了产生1摩尔5-磷酸核酮糖，有2摩尔NAD⁺被还原。
