The enzymic interconversion of uridine diphosphogalactose and uridine diphosphoglucose.

The reversible transformation of galactose into glucose in biological systems is important both for the utilization of dietary galactose as fuel (via hexose 6-phosphate) and for the biosynthesis of complex galactose-containing compounds from glucose or acetate. The first step in the metabolism of galactose in both yeast and animal tissues is phosphorylation in the 1 position of the hexose to form cw-Gal-l-P’ (l-3). The interconversion of the hexoses then takes place according to the following equations, in which uridine diphosphoglucose functions catalytically.