UDPG Pyrophosphorylase Research Articles

Stimulation of glucose metabolism in Trichophyton mentagrophytes during incubation in increased carbon dioxide tension.

SUMMARY: An inducible UDPG pyrophosphorylase (UTP:α-d-glucose-1-phosphate uridyltransferase, EC 2.7.7.9) has been demonstrated in cell-free extracts from Trichophyton mentagrophytes incubated in increasing atmospheric tensions of carbon dioxide. Assays of related enzymes have shown that UDPG pyrophosphorylase is not the only enzyme induced by CO2. Glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and glucose-phosphate isomerase (EC 5.3.1.7) were more strongly stimulated than UDPG pyrophosphorylase. Hexokinase (EC 2.7.1.1), phosphoglucomutase (EC 2.7.5.1) and 6-phosphogluconate dehydrogenase (EC 1.1.1.43) were more weakly stimulated than UDPG pyrophosphorylase. The stimulation of UDPG pyrophosphorylase does not occur as a result of sequential induction.

Mutations in Escherichia coli that affect uridine diphosphate glucose pyrophosphorylase activity and galactose fermentation

The metabolism of galactose was studied in two galactose-non-fermenting mutants which were isolated from Escherichia coli strain K12 and classified genetically as Group E by Drs. J. and E. M. Lederberg. One of them, W4597, was found to have a single defect in UDPG pyrophosphorylase (UTP: α-d-glucose-1-phosphate uridylyltranserase, EC 2.7.7.9) and to be normal in galactokinase (ATP: d-galactose 1-phosphotransferase, EC 2.7.1.6), Gal-1-P uridyl transferase (UDP glucose: α-d-galactose-1-phosphate uridylyl transferase, EC 2.7.7.12), UDP galactose 4-epimerase (UDP glucose 4-epimerase, EC 5.1.3.2), phosphoglucomutase (d-glucose-1,6-diphosphate: d-glucose-1-phosphate phosphotransferase, EC 2.7.5.1), and also in galactose permease. Non-fermentation of galactose in this strain was, therefore, ascribed to the defect of UDPG pyrophosphorylase. The other strain, W3142, was shown to have a secondary defect in galactokinase in addition to a defect in UDPG pyrophosphorylase. When grown in the presence of galactose, W4597 accumulated intracellularly a large amount of Gal-1-P.The intracellular levels of UDPG and uridine diphosphate galactose were shown to be much lower in both of these strains than in wild-type strains, irrespective of the presence or absence of galactose in the growth media. The sugars of their cell walls were composed only of an aldoheptose, hexosamines and a smaller amount of glucose; any traces of galactose, which is present in wild type cell walls, were not detected in their cell walls.

Levels of activity of the enzymes of the glycogen cycle in rat tissues

Levels of phosphorylase, UDPG pyrophosphorylase, and phosphoglucomutase activities have been studied in rat tissues. Glycogen content of the same tissues has been determined in fed and fasted rats. The results obtained appear to be compatible with a cyclic mechanism of glycogen synthesis and degradation.