Uridine diphosphate-glucose

The breakdown of glycogen to glucose 1-phosphate is catalyzed by phosphorylase. Glycogen synthesis involves a different pathway via uridine diphosphate glucose and glycogen synthase (Figure 18-1). 

UDPG + PP = G-l-P + UTP Uridine diphosphate glucose pyro-phosphorylase... 

L2. Leloir, L. F., The enzymatic transformation of uridine diphosphate glucose into a galactose derivative. Arch. Biochem. Biophys. 33, 186-190 (1951). 

Strominger, J. L., Kalckar, H. M., Axelrod, J., and Maxwell, E. S., Enzymatic oxidation of uridine diphosphate glucose to uridine diphosphate glucuronic acid. 

It should be noted, in this connection, that there are pyridine nucleotide dehydrogenases which catalyze redox reactions which must occur in two steps. Hydroxymethylglutaryl CoA reductase (discussed on p. 51) is one example. Another is uridine diphosphate-glucose dehydrogenase, which catalyzes the oxidation of the C—6 of the glucose (i.e., a primary alcohol) to a carboxyl group. In both cases, there are two molecules of pyridine nucleotide required, and the overall reactions are essentially irreversible. The former enzyme, with A stereospecificity for the pyridine nucleotide, catalyzes the reduction of an acyl-CoA group... 

Figure 6.17 A summary of the reactions in the pathway for glycogen synthesis. Full details of the pathway are given in Figure 6.18. UDPG is the abbreviation for uridine diphosphate glucose.

F5. Fevery, J., Leroy, P., Van De Vijver, M., and Heirwegh, K. P. M., Structures of bilirubin conjugates synthesized in vitro from bilirubin and uridine diphosphate glucuronic acid, uridine diphosphate glucose or uridine diphosphate xylose by preparations from rat liver. Biochem. J. 129, 635-644 (1972). 

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