Kinetic and conformational studies of the orotate phosphoribosyltransferase:orotidine-5'-phosphate decarboxylase enzyme complex from mouse Ehrlich ascites cells.

@article{Traut1977KineticAC,
  title={Kinetic and conformational studies of the orotate phosphoribosyltransferase:orotidine-5'-phosphate decarboxylase enzyme complex from mouse Ehrlich ascites cells.},
  author={T. Traut and M. E. Jones},
  journal={The Journal of biological chemistry},
  year={1977},
  volume={252 23},
  pages={
          8372-81
        }
}
Complex U is composed of orotate phosphoribosyltransferase (EC 2.4.2.10) and orotidine-5’-phosphate decarboxylase (EC 4.1.1.23), the last two enzymes of the de nouo pathway for pyrimidine biosynthesis. Since the two enzymes have proved inseparable so far, the equilibrium constant for the phosphoribosyltransferase activity has been determined under conditions where the decarboxylase activity was totally inhibited by B-azaUMP. The K,, for orotate phosphoribosyltransferase in the direction of… Expand
Does the bifunctional uridylate synthase channel orotidine 5'-phosphate? Kinetics of orotate phosphoribosyltransferase and orotidylate decarboxylase activities fit a noninteracting sites model.
TLDR
The appropriate computer simulation demonstrates that low transient levels of OMP and protection of the intermediate are provided for strictly by the kinetic parameters of orotate phosphoribosyltransferase, OMP decarboxylase, and the nucleotidase. Expand
Dependence of the catalytic activities on the aggregation and conformation states of uridine 5'-phosphate synthase.
TLDR
Initial velocity studies with the enzyme in the different native states show that all three forms of UMP synthase have phosphoribosyltransferase activity but that the OMP decarboxylase is either uniquely or at least predominantly associated with the 5.6S form. Expand
Orotate phosphoribosyltransferase and orotidylate decarboxylase from Crithidia luciliae: subcellular location of the enzymes and a study of substrate channeling.
TLDR
The particulate location of OPRTase and ODCase was considered to be favorable for channeling of orotidine-5'-monophosphate (OMP), the product of the first enzyme and substrate for the second, and the efficiency of channeling was high, with an approximate 50-fold preference for endogenous OMP. Expand
Significance of the enzyme complex that synthesizes UMP in Ehrlich ascites cells.
  • T. Traut
  • Biology, Medicine
  • Archives of biochemistry and biophysics
  • 1980
TLDR
The results suggest that the capability for channeling OMP may have been important in evolving the enzyme complex found in mammalian cells. Expand
Uridine-5'-phosphate synthase: evidence for substrate cycling involving this bifunctional protein.
  • T. Traut
  • Chemistry, Medicine
  • Archives of biochemistry and biophysics
  • 1989
TLDR
The present studies show that UMP synthase has cooperative kinetics toward OMP, and that a substrate cycle involving orotate phosphoribosyltransferase, cytoplasmic nucleotidase, and uridine phosphorylase maintains the cyclic interconversion. Expand
Dependence of the aggregation and conformation states of uridine 5'-phosphate synthase on pyrimidine nucleotides. Evidence for a regulatory site.
TLDR
Evidence for a regulatory site, distinct from either of the two catalytic sites, which appears to mediate the conversion of the 5.6S form upon binding certain pyrimidine nucleotides (OMP, UMP, and 6-azaUMP) is presented. Expand
Orotate phosphoribosyltransferase: orotidylate decarboxylase (Ehrlich ascites cell).
TLDR
This chapter describes purification procedure related to the orotate phosphoribosyltransferase enzyme, useful when one wishes to estimate how effective inhibitors of the decarboxylase are when the OMP level is that maintained at a steady-state level by the complex itself. Expand
Intrinsic Activity and Stability of Bifunctional Human UMP Synthase and Its Two Separate Catalytic Domains, Orotate Phosphoribosyltransferase and Orotidine-5′-phosphate Decarboxylase (*)
TLDR
These studies address the question of why the last two reactions in pyrimidine nucleotide synthesis are catalyzed by a bifunctional enzyme in mammalian cells, but by two separate enzymes in microorganisms by hypothesizing that the covalent union in UMP synthase stabilizes the domains containing the respective catalytic centers. Expand
Kinetic mechanism of orotate phosphoribosyltransferase from Salmonella typhimurium.
TLDR
It is proposed that PRTases may involve a direct-transfer mechanism but with low bond order to the leaving pyrophosphate moiety and attacking base, and may have implications for similar prior work on the yeast enzyme. Expand
Mammalian synthesis of UMP from orotate: the regulation of and conformers of complex U.
TLDR
It is suggested that the 4.8 S conformer might be expected to exist in the cytosol, in vivo, and whether Complex U is a multifunctional protein so that the two enzymatically active centers reside on a singly polypeptide chain. Expand
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References

SHOWING 1-3 OF 3 REFERENCES
Advances in Enzyme Regulation.G. Weber
Reeulation of Purine Biosvnthesis. D
  • J. Biochem
  • 1972
Reeulation of Purine Biosvnthesis
  • J . Biochem .
  • 1972