EC - Dihydroorotate dehydrogenase (NAD+)

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IntEnz Enzyme Nomenclature


Accepted name:
dihydroorotate dehydrogenase (NAD+)
Other names:
orotate reductase (NADH)
orotate reductase (NADH2)
DHOdehase [ambiguous]
DHOD [ambiguous]
DHODase [ambiguous]
dihydroorotate oxidase
Systematic name:
(S)-dihydroorotate:NAD+ oxidoreductase




Binds FMN, FAD and a [2Fe-2S] cluster. The enzyme consists of two subunits, an FMN binding catalytic subunit and a FAD and iron-sulfur binding electron transfer subunit [4]. The reaction, which takes place in the cytosol, is the only redox reaction in the de-novo biosynthesis of pyrimidine nucleotides. Other class 1 dihydroorotate dehydrogenases use either fumarate (EC or NADP+ (EC as electron acceptor. The membrane bound class 2 dihydroorotate dehydrogenase (EC uses quinone as electron acceptor.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0004589
CAS Registry Number: 37255-26-8
UniProtKB/Swiss-Prot: (98) [show] [UniProt]


  1. Friedmann, H.C. and Vennesland, B.
    Purification and properties of dihydroorotic acid dehydrogenase.
    J. Biol. Chem. 233: 1398-1406 (1958).
  2. Friedmann, H.C. and Vennesland, B.
    Crystalline dihydroorotic dehydrogenase.
    J. Biol. Chem. 235: 1526-1532 (1960).
  3. Lieberman, I. and Kornberg, A.
    Enzymic synthesis and breakdown of a pyrimidine, orotic acid. I. Dihydro-orotic dehydrogenase.
    Biochim. Biophys. Acta 12: 223-234 (1953).
  4. Nielsen, F. S., Andersen, P. S., Jensen, K. F.
    The B form of dihydroorotate dehydrogenase from Lactococcus lactis consists of two different subunits, encoded by the pyrDb and pyrK genes, and contains FMN, FAD, and [FeS] redox centers.
    J. Biol. Chem. 271: 29359-29365 (1996). [PMID: 8910599]
  5. Rowland, P., Norager, S., Jensen, K. F., Larsen, S.
    Structure of dihydroorotate dehydrogenase B: electron transfer between two flavin groups bridged by an iron-sulphur cluster.
    Structure 8: 1227-1238 (2000). [PMID: 11188687]
  6. Kahler, A. E., Nielsen, F. S., Switzer, R. L.
    Biochemical characterization of the heteromeric Bacillus subtilis dihydroorotate dehydrogenase and its isolated subunits.
    Arch. Biochem. Biophys. 371: 191-201 (1999). [PMID: 10545205]
  7. Marcinkeviciene, J., Tinney, L. M., Wang, K. H., Rogers, M. J., Copeland, R. A.
    Dihydroorotate dehydrogenase B of Enterococcus faecalis. Characterization and insights into chemical mechanism.
    Biochemistry 38: 13129-13137 (1999). [PMID: 10529184]

[EC created 1972, modified 2011]