title: Uridine diphosphate-4-keto-glucose, an intermediate in the uridine diphosphate-galactose-4-epimerase reaction.
abstract: When UDP-galactose 4-epimerase (EC 5.1.3.2) from Escherichia coli is incubated with UDP-galactose, then reduced with NaB(3)H(4), label is found in UDP-glucose and UDP-galactose. Enzymatic and chemical degradation demonstrates that the label is bound to carbon 4 of the glycosyl moieties. These results provide direct evidence for the existence of UDP-4-keto-glucose as an enzyme-bound intermediate in the epimerization reaction, and they exclude the formation of a 3-keto intermediate.
mesh_terms: D000429:Alcohol Oxidoreductases; D002262:Carboxy-Lyases; D055598:Chemical Phenomena; D002621:Chemistry; D002854:Chromatography, Paper; D003454:Cryptococcus / Q000201:enzymology; D004590:Electrophoresis, Paper; D004926:Escherichia coli / Q000201:enzymology; D005690:Galactose; D005947:Glucose; D005965:Glucuronates; D007535:Isomerases; D007659:Ketones; D010084:Oxidation-Reduction; D011485:Protein Binding; D014316:Tritium; D014500:Uracil Nucleotides
chemical_list: D005965:Glucuronates; D007659:Ketones; D014500:Uracil Nucleotides; D014316:Tritium; D000429:Alcohol Oxidoreductases; D002262:Carboxy-Lyases; D007535:Isomerases; D005947:Glucose; D005690:Galactose