IUBMB Enzyme Nomenclature


Accepted name: dihydroorotate dehydrogenase (NAD+)

Reaction: (S)-dihydroorotate + NAD+ = orotate + NADH + H+

Other name(s): orotate reductase (NADH); orotate reductase (NADH2); DHOdehase (ambiguous); DHOD (ambiguous); DHODase (ambiguous); dihydroorotate oxidase, pyrD (gene name)

Systematic name: (S)-dihydroorotate:NAD+ oxidoreductase

Comments: 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: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 37255-26-8


1. Friedmann, H.C. and Vennesland, B. Purification and properties of dihydroorotic acid dehydrogenase. J. Biol. Chem. 233 (1958) 1398-1406. [PMID: 13610849]

2. Friedmann, H.C. and Vennesland, B. Crystalline dihydroorotic dehydrogenase. J. Biol. Chem. 235 (1960) 1526-1532. [PMID: 13825167]

3. Lieberman, I. and Kornberg, A. Enzymic synthesis and breakdown of a pyrimidine, orotic acid. I. Dihydro-orotic dehydrogenase. Biochim. Biophys. Acta 12 (1953) 223-234. [PMID: 13115431]

4. Nielsen, F.S., Andersen, P.S. and 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 (1996) 29359-29365. [PMID: 8910599]

5. Rowland, P., Nørager, S., Jensen, K.F. and Larsen, S. Structure of dihydroorotate dehydrogenase B: electron transfer between two flavin groups bridged by an iron-sulphur cluster. Structure 8 (2000) 1227-1238. [PMID: 11188687]

6. Kahler, A.E., Nielsen, F.S. and Switzer, R.L. Biochemical characterization of the heteromeric Bacillus subtilis dihydroorotate dehydrogenase and its isolated subunits. Arch. Biochem. Biophys. 371 (1999) 191-201. [PMID: 10545205]

7. Marcinkeviciene, J., Tinney, L.M., Wang, K.H., Rogers, M.J. and Copeland, R.A. Dihydroorotate dehydrogenase B of Enterococcus faecalis. Characterization and insights into chemical mechanism. Biochemistry 38 (1999) 13129-13137. [PMID: 10529184]

[EC created 1972, modified 2011]

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