title: Purification and properties of myo-inositol-1-phosphate dehydrogenase from germinating mung bean seeds.
abstract: 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.
mesh_terms: D007887:Fabaceae; D007526:Isoelectric Point; D007700:Kinetics; D008970:Molecular Weight; D009243:NAD / Q000378:metabolism; D010946:Plants, Medicinal; D012274:Ribulosephosphates / Q000378:metabolism; D012639:Seeds / Q000201:enzymology*; D013050:Spectrometry, Fluorescence; D013401:Sugar Alcohol Dehydrogenases / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D012274:Ribulosephosphates; D009243:NAD; C031524:ribulose 5-phosphate; D013401:Sugar Alcohol Dehydrogenases; C021823:myo-inositol-1-phosphate dehydrogenase