PMID:3513846
| Citation |
Rasmussen, UB, Mygind, B and Nygaard, P (1986) Purification and some properties of uracil phosphoribosyltransferase from Escherichia coli K12. Biochim. Biophys. Acta 881:268-75 |
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| Abstract |
Uracil phosphoribosyltransferase from Escherichia coli K12 was purified to homogeneity as determined by polyacrylamide gel electrophoresis. For this purpose a pyrimidine-requiring strain harboring the upp gene on a ColE1 plasmid was used, which showed 15-times higher uracil phosphoribosyltransferase activity in a crude extract. When this strain was grown under conditions of uracil starvation, an additional 10-times elevation of the enzyme activity was obtained. The molecular weight of uracil phosphoribosyltransferase was determined to be 75000; the enzyme consists of three subunits with a molecular weight of 23500. Uracil phosphoribosyltransferase is specific for uracil and some uracil analogues. The apparent Km values for uracil and PRib-PP were 7 microM and 300 microM, respectively. As an effector of enzyme activity, GTP lowered the Km for PRib-PP to 90 microM and increased the Vmax value 2-fold, but had no effect on the Km for uracil. The effect of GTP was found to be pH-dependent. The enzymatic characterization of uracil phosphoribosyltransferase and the observed regulation of its synthesis emphasizes the role of the enzyme in pyrimidine salvage. |
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| Keywords |
Chromatography, Affinity; Electrophoresis, Polyacrylamide Gel; Escherichia coli/enzymology; Escherichia coli/genetics; Gene Amplification; Guanosine Triphosphate/metabolism; Kinetics; Molecular Weight; Pentosyltransferases/isolation & purification; Plasmids; Pyrimidines/metabolism; Substrate Specificity |
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