NADH-dependent keto-reducing

UDP-Glc is converted into UDP-Gal by a reaction catalyzed by UDP-Gal-4-epimerase. The enzyme is NAD dependent and the first reaction that it catalyzes is the oxidation of C-4 of UDP-Glc to give the 4-keto intermediate and NADH. The complex undergoes a conformational change and the NADH-product stereospecifically reduces the keto group to give the D-galactose structure [13-15] (see Fig. 10.6). 

Diverse soluble enzymes, called aldo-keto reductases. cany out bioreduction of aldehydes and ketones. They are found in the liver and other tissues (e.g.. kidney). As a general class, these soluble en7.ynie.s have similar physi-ochemical properties and broad substrate specificities and require NADW as a cofactor. Oxidoreductase enzymes that catty out both oxidation and reduction reactions also can reduce aldehydes and ketones. " For example. Ihe important liver alcohol dehydrogenase is an NAD -dependent oxido-icductase that oxidizes ethanol and other aliphatic alcohols to aldehydes and ketones. In the presence of NADH or... 

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