Reactions
Aldose reductase catalyzes the NADPH-dependent conversion of glucose to sorbitol, the first step in polyol pathway of glucose metabolism. The second and last step in the pathway is catalyzed by sorbitol dehydrogenase, which catalyzes the NAD-linked oxidation of sorbitol to fructose. Thus, the polyol pathway results in conversion of glucose to fructose with stoichiometric utilization of NADPH and production of NADH.
- glucose + NADPH + H+ → sorbitol + NADP+
Galactose is also a substrate for the polyol pathway, but the corresponding keto sugar is not produced because sorbitol dehydrogenase is incapable of oxidizing galactitol. Nevertheless, aldose reductase can catalyze the reduction of galactose to galactitol
- galactose + NADPH + H+ → galactitol + NADP+
Read more about this topic: Aldose Reductase
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