IUBMB Enzyme Nomenclature


Accepted name: dihydroorotate dehydrogenase (quinone)

Reaction: (S)-dihydroorotate + a quinone = orotate + a quinol

Other name(s): dihydroorotate:ubiquinone oxidoreductase; (S)-dihydroorotate:(acceptor) oxidoreductase; (S)-dihydroorotate:acceptor oxidoreductase; DHOdehase (ambiguous); DHOD (ambiguous); DHODase (ambiguous); DHODH

Systematic name: (S)-dihydroorotate:quinone oxidoreductase

Comments: This Class 2 dihydroorotate dehydrogenase enzyme contains FMN [4]. The enzyme is found in eukaryotes in the mitochondrial membrane, and in some Gram negative bacteria associated with the cytoplasmic membrane [2,5]. 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: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 59088-23-2


1. Forman, H.J. and Kennedy, J. Mammalian dihydroorotate dehydrogenase: physical and catalytic properties of the primary enzyme. Arch. Biochem. Biophys. 191 (1978) 23-31. [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 (1986) 11386-11392. [PMID: 3733756]

3. 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 (1998) 414-422. [PMID: 9693067]

4. Fagan, R.L., Nelson, M.N., Pagano, P.M. and Palfey, B.A. Mechanism of flavin reduction in Class 2 dihydroorotate dehydrogenases. Biochemistry 45 (2006) 14926-14932. [PMID: 17154530]

5. Björnberg, O., Grüner, A.C., Roepstorff, P. and 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 (1999) 2899-2908. [PMID: 10074342]

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

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