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.
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