Polyol dehydrogenases

034106 L-Amino-acid oxidase (1.4.3.2) acts non-specifi-cally. 

034145 An extracellular enzyme is present which decomposes starch to a crystalline dextrin. 

034109 Catalase (1.11.1.6) is present (hydrogen peroxide decomposed by an enzyme containing a heme or porphyrin structural group). 

034110 Catalase-pseudo (an enzyme not containing a heme structural unit) decomposes hydrogen peroxide to water and oxygen. 

034125 3-D-Glucosidase [Gentiobiase, Cellobiase, Amyg-dalase] (3.2.1.21) is present. 

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Further studies on liver polyol dehydrogenases (e.g., Hll, Mil, T3, W14, W19) revealed the existence of a number of enzymes catalyzing reactions which can be written as follows ... 

Different preparative procedures have been shown to yield protein fractions which are able to catalyze different types of reactions with respect to their requirement of either NAD or NADP as coenzymes [cf. Eqs. (19), (20), and (21)]. In sera of mice poisoned by carbon tetrachloride we found polyol dehydrogenases catalyzing the oxidation of the following polyols (a) with NAD sorbitol, ribitol, mannitol (b) with NADP sorbitol, ribitol. Erythritol and mt/o-inositol were not attacked at all. Figures 8 and 9 show the results of these determinations performed at pH 9.6. In the NAD system sorbitol and ribitol are oxidized at exactly the same rate, while in the NADP system ribitol does not reach the rate of sorbitol. The ratio NAD NADP for sorbitol is calculated to be 4.20 and for ribitol 5.50. Mannitol is oxidized at 23% of the rate of sorbitol. 

The reactivity of xylitol in the polyol dehydrogenase reactions has been extensively studied for its relations to pentosuria. Xylitol was found to be oxidized in two ways (a) to L-xylulose by a highly specific NADP-requiring dehydrogenase and (b) to D-xylulose by a NAD-linked enzyme with lesser substrate specificity ... 

Fic. 8. NAD polyol dehydrogenase in sera of CCl4-poisoned mice sorbitol, ribitol, and mannitol oxidation (pH 9.6 polyols as substrates). 

The evidence that polyol dehydrogenases can be considered as a group of different enzymes is supported by the finding that all reactions exhibit a specific stereochemical pattern (e.g., Mil, S13, V3). 

The role that polyol dehydrogenases play in metabolism has scarcely been elucidated. Approaches were made by investigating the metabolic fate of C14-labeled sorbitol after oral and parenteral administration. It has been found that in normal animals C1402 was expired following the administration of labeled sorbitol, while eviscerated, liverless subjects showed no C1402 expiration under these conditions, thus confirming... 

Clinical Implications of Polyol Dehydrogenases 5.6.1. Serum SDH Activity in Disease States... 

The Role of Polyol Dehydrogenases in Essential Congenital Pentosuria... 

Hll. Hollman, S., and Touster, O., The L-xylulose-xylitol enzyme and other polyol dehydrogenases of guinea pig liver mitochondria. ]. Biol. Chem. 225, 87-102 (1957). 

Dehydrogenase, 6-Phosphogluconate Dehydrogenase, Glutathione Reductase, Methemoglobin Reductase, Polyol Dehydrogenases (Bruns and Werners), 5, 237... 

This enzyme [EC 1.1.1.21], also known as aldehyde reductase and polyol dehydrogenase (NADP ), catalyzes the reaction of an alditol with NAD(P) to generate an aldose and NAD(P)H. The enzyme exhibits a broad specificity for the alditol. 

ACTIN ASSEMBLY KINETICS POLYNUCLEOTIDE S -HYDROXYL-KINASE POLYNUCLEOTIDE PHOSPHORYLASE Polyol dehydrogenase,... 

IDH) from Candida utilis, also known as sorbitol or polyol dehydrogenase[35, 85. Reduction of the ketone occurs to give the alcohol with (S)-stereochemistry. The corresponding (R)-alcohol was obtained by non-stereoselective reduction of the ketone with NaBH(OAc)3 and the (S)-epimer was selectively removed by IDH-catalyzed oxidation. L-Xylose and 2-deoxy-D-orobino-hexose were synthesized by each of these two processes, respectively. 

Polyol dehydrogenase. Sorbitol dehydrogenase. L-iditol + NAD(+) = L-sorbose + NADH. 

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