Uridine glucose

Sugar nucleotides are formed from sugar-l-phosphates and nucleoside triphosphates by specific pyrophosphorylase enzymes (Figure 23.18). For example, UDP-glucose pyrophosphorylase catalyzes the formation of UDP-glucose from glucose-l-phosphate and uridine 5 -triphosphate ... 

Other nucleoside diphosphate sugar compounds are known, eg, UDPGal. In addition, the same sugar may be linked to different nucleotides. For example, glucose may be linked to uridine (as shown above) as well as to guanosine, thymidine, adenosine, or cy-tidine nucleotides. 

Glucose Diphosphate Uridine Figure 18-2. Uridine diphosphate giucose (UDPGic). 

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). 

Figure 47-7. Pathway of biosynthesis of dolichol-P-P-oligosaccharide. The specific linkages formed are indicated in Figure 47-8. Note that the first five internal mannose residues are donated by GDP-mannose, whereas the more external mannose residues and the glucose residues are donated by dolichol-P-mannose and dolichol-P-glucose. (UDP, uridine diphosphate Dol, dolichol P, phosphate UMP, uridine monophosphate GDP, guanosine diphosphate M, mannose G, glucose.)...

D-Galaktose entsteht nach L. F. Leloir in der Natur aus D-Glucose durch enzymatische Konfigurationsumkehr des C-4 auf der Stufe der a-1-Phosphate. Die Enzyme, die diese Inversion vollbringen, benotigen als Cofaktor Uridin-diphosphat-glucose (UDPG). Nun konnte. aus... 

Synthesis of sucrose 6 -phosphate by an enzymic method using uridine 5 -(a-D-glucopyranosyl diphosphate) plus D-glucose 6-phosphate has been reported.126-131 The first, unambiguous, chemical synthesis of sucrose 6 -phosphate was achieved by Buchanan and coworkers.18 The reaction of 2,3,4,6,l, 3, 4 -hepta-0-acetylsucrose, prepared by five steps of synthesis, with cyanoethyl phosphate in pyridine gave a crude product from which sucrose 6 -phosphate was isolated as the barium salt. 

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. 

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