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MetaCyc Reaction:

Superclasses: Reactions Classified By Conversion TypeSimple ReactionsChemical ReactionsComposite ReactionsElectron-Transfer-Reactions
Reactions Classified By SubstrateSmall-Molecule Reactions

EC Number:

Enzymes and Genes:

Arabidopsis thaliana col: dihydroorotate dehydrogenaseInferred from experiment: PYRD

In Pathway: UMP biosynthesis

Supersedes EC number:

Transport reaction diagram

Reaction Locations: inner membrane (sensu Gram-negative Bacteria)

The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the Enzyme Commission system.

Mass balance status: Balanced.

Instance reaction:
(S)-dihydroorotate + a menaquinone[inner membrane] → orotate + a menaquinol[inner membrane] (

Enzyme Commission Primary Name: dihydroorotate dehydrogenase (quinone)

Enzyme Commission Synonyms: dihydroorotate:ubiquinone oxidoreductase, (S)-dihydroorotate:(acceptor) oxidoreductase, (S)-dihydroorotate:acceptor oxidoreductase, DHOdehase (ambiguous), DHOD (ambiguous), DHODase (ambiguous), DHODH

Standard Gibbs Free Energy (ΔrG in kcal/mol): 2.2177582Inferred by computational analysis [Latendresse13]

Enzyme Commission Summary:
This Class 2 dihydroorotate dehydrogenase enzyme contains FMN [Fagan06]. The enzyme is found in eukaryotes in the mitochondrial membrane and in some Gram negative bacteria associated with the cytoplasmic membrane [Hines86, Bjornberg99]. The reaction is the only redox reaction in the de-novo biosynthesis of pyrimidine nucleotides [Hines86, Fagan06]. The best quinone electron acceptors for the enzyme from bovine liver are coenzymes ubiquinone-6 and ubiquinone-7, although simple quinones, such as benzoquinone, can also act as acceptor but at lower rates [Hines86]. Methyl-, ethyl-, tert-butyl and benzyl-(S)-dihydroorotates are also substrates, but 1- and 3-methyl and 1,3-dimethyl methyl-(S)-dihydroorotates are not [ [Hines86]. Class 1 dihydroorotate dehydrogenases use either fumarate ( EC, NAD+ ( EC or NADP+ ( EC as electron acceptor.

Citations: [Forman78, Bader98]

Gene-Reaction Schematic

Gene-Reaction Schematic

Unification Links: KEGG:R01868, Rhea:18073

Relationship Links: BRENDA:EC:, ENZYME:EC:, IUBMB-ExplorEnz:EC:, UniProt:RELATED-TO:O76140

Revised 13-Jan-2011 by Caspi R, SRI International


Bader98: Bader B, Knecht W, Fries M, Loffler M (1998). "Expression, purification, and characterization of histidine-tagged rat and human flavoenzyme dihydroorotate dehydrogenase." Protein Expr Purif 13(3);414-22. PMID: 9693067

Bjornberg99: Bjornberg O, Gruner AC, Roepstorff P, Jensen KF (1999). "The activity of Escherichia coli dihydroorotate dehydrogenase is dependent on a conserved loop identified by sequence homology, mutagenesis, and limited proteolysis." Biochemistry 38(10);2899-908. PMID: 10074342

Fagan06: Fagan RL, Nelson MN, Pagano PM, Palfey BA (2006). "Mechanism of flavin reduction in class 2 dihydroorotate dehydrogenases." Biochemistry 45(50);14926-32. PMID: 17154530

Forman78: Forman HJ, Kennedy J (1978). "Mammalian dihydroorotate dehydrogenase: physical and catalytic properties of the primary enzyme." Arch Biochem Biophys 191(1);23-31. PMID: 216313

Hines86: Hines V, Keys LD, Johnston M (1986). "Purification and properties of the bovine liver mitochondrial dihydroorotate dehydrogenase." J Biol Chem 261(24);11386-92. PMID: 3733756

Latendresse13: Latendresse M. (2013). "Computing Gibbs Free Energy of Compounds and Reactions in MetaCyc."

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by Pathway Tools version 19.5 (software by SRI International) on Sun May 1, 2016, biocyc14.