Glucose pyrophosphorylase

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 ... 

FIGURE 23.18 The UDP-glucose pyrophosphorylase reaction is a phosphoanhydride exchange, with a phosphoryl oxygen of glu-cose-l-P attacking the m-phosphorus of UTP to form UDP-glucose and pyrophosphate. 

ZRENNER, R., WILLMITZER, L SONNEWALD, U., Analysis of the expression of potato uridinediphosphate-glucose pyrophosphorylase and its inhibition by antisense RNA, Planta, 1993,190, 247-252. 

There is some difficulty in correlating results of PAN exposure in vfvo with the above types of in vitro studies. For example, UDP glucose pyrophosphorylase is very susceptible to PAN in vitro, but in vivo there is a stimulation of enzymatic activity (at 112 ppm for 6 min). It is also... 

Hall, M. A., and L. Ordin. Subcellular location of phosphoglucomutase and UDP glucose pyrophosphorylase in avena coleoptiles. Physiol. Plant. 20 624-633, I%7. 

This enzyme [EC Unil], also known as ADP-glucose synthase and ADP-glucose pyrophosphorylase, catalyzes the reaction of a-o-glucose 1-phosphate with ATP to produce ADP-glucose and pyrophosphate. 

In fluorine-18 chemistry some enzymatic transformations of compounds already labelled with fluorine-18 have been reported the synthesis of 6-[ F] fluoro-L-DOPA from 4-[ F]catechol by jS-tyrosinase [241], the separation of racemic mixtures of p F]fluoroaromatic amino acids by L-amino acylase [242] and the preparation of the coenzyme uridine diphospho-2-deoxy-2-p F]fluoro-a-o-glucose from [ F]FDG-1-phosphate by UDP-glucose pyrophosphorylase [243]. In living nature compounds exhibiting a carbon-fluorine bond are very rare. 

Sowokinos, J. R. (2001a). Pyrophosphorylase in Solanum tuberosum L. Allelic and isozyme patterns of UDP-glucose pyrophosphorylase as a marker for cold-sweetening resistance in potatoes. American Journal of Potato Research, 78, 57-64. 

For many biosynthetic reactions that liberate pyrophosphatase activity makes the process more favorable energetically, tending to make these reactions irreversible. In plants, this enzyme is present in plastids but absent from the cytosol. As a result, the cytosol of leaf cells contains a substantial concentration of PP,— enough ( 0.3 him) to make reactions such as that catalyzed by UDP-glucose pyrophosphorylase (Fig. 15-7) readily reversible. Recall from Chapter 14 (p. 527) that the cytosolic isozyme of phosphofructokinase in plants uses PPi, not ATP, as the phosphoryl donor. 

Review of the role of ADP-glucose pyrophosphorylase in the synthesis of amylose and amylopectin in starch granules. 

In contrast to animals, bacteria such as E. coli synthesize glycogen via ADP-glucose rather than UDP-glucose.88 ADP-glucose is also the glucosyl donor for synthesis of starch in plants. The first step in the biosynthesis (Eq. 20-18) is catalyzed by the enzyme ADP-glucose pyrophosphorylase (named for the reverse reaction). 

Turnquist RL, Hansen RG(I973) Uridine diphosphoryl glucose pyrophosphorylase. In Boyer PD (ed) The Enzymes Vol VIII. Academic Press, New York, 51... 

UDP-glucose pyrophosphorylase catalyzes the synthesis of UDP-glucose (see Fig. 1) from UTP and glucose 1-phosphate ... 

ADP-glucose Pyrophosphorylase Kinetic Properties and Quaternary Structure... 

Residues that are not identical but similar in potato tuber ADP-glucose pyrophosphorylase large subunit. 

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