EC - Dihydroorotate dehydrogenase (quinone)

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IntEnz Enzyme Nomenclature


Accepted name:
dihydroorotate dehydrogenase (quinone)
Other names:
dihydroorotate:ubiquinone oxidoreductase
(S)-dihydroorotate:(acceptor) oxidoreductase
(S)-dihydroorotate:acceptor oxidoreductase
Systematic name:
(S)-dihydroorotate:quinone oxidoreductase




This Class 2 dihydroorotate dehydrogenase enzyme contains FMN [4]. The enzyme is found in eukaryotes in the mitochondrial membrane, in cyanobacteria, and in some Gram-negative and Gram-positive bacteria associated with the cytoplasmic membrane [2,5,6]. The reaction is the only redox reaction in the de-novo biosynthesis of pyrimidine nucleotides [2,4]. The best quinone electron acceptors for the enzyme from bovine liver are ubiquinone-6 and ubiquinone-7, although simple quinones, such as benzoquinone, can also act as acceptor at lower rates [2]. Methyl-, ethyl-, tert-butyl and benzyl-(S)-dihydroorotates are also substrates, but methyl esters of (S)-1-methyl and (S)-3-methyl and (S)-1,3-dimethyldihydroorotates are not [2]. Class 1 dihydroorotate dehydrogenases use either fumarate (EC, NAD+ (EC or NADP+ (EC as electron acceptor.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , NIST 74 , UniPathway
Protein domains and families: PROSITE:PDOC00708
Structural data: CSA , EC2PDB
Gene Ontology: GO:0004152
CAS Registry Number: 59088-23-2
UniProtKB/Swiss-Prot: (393) [show] [UniProt]


  1. Forman, H.J. and Kennedy, J.
    Mammalian dihydroorotate dehydrogenase: physical and catalytic properties of the primary enzyme.
    Arch. Biochem. Biophys. 191: 23-31 (1978). [PMID: 216313]
  2. Hines, V., Keys, L.D., III and Johnston, M.
    Purification and properties of the bovine liver mitochondrial dihydroorotate dehydrogenase.
    J. Biol. Chem. 261: 11386-11392 (1986). [PMID: 3733756]
  3. Hines, V., Keys, L.D., III and Johnston, M.
    Erratum report. Purification and properties of the bovine liver mitochondrial dihydroorotate dehydrogenase.
    J. Biol. Chem. 262: 15322 (1987).
  4. Bader, B., Knecht, W., Fries, M. and Löffler, M.
    Expression, purification, and characterization of histidine-tagged rat and human flavoenzyme dihydroorotate dehydrogenase.
    Protein Expr. Purif. 13: 414-422 (1998). [PMID: 9693067]
  5. Fagan, R.L., Nelson, M.N., Pagano, P.M. and Palfey, B.A.
    Mechanism of flavin reduction in class 2 dihydroorotate dehydrogenases.
    Biochemistry 45: 14926-14932 (2006). [PMID: 17154530]
  6. Bjornberg, O., Gruner, A. C., Roepstorff, P., Jensen, K. F.
    The activity of Escherichia coli dihydroorotate dehydrogenase is dependent on a conserved loop identified by sequence homology, mutagenesis, and limited proteolysis.
    Biochemistry 38: 2899-2908 (1999). [PMID: 10074342]

[EC created 1983, transferred 2009 to EC, modified 2011]