The Enzyme Database

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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, 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: 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. [DOI] [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. [DOI] [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. [DOI] [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. [DOI] [PMID: 10074342]
6.  Nara, T., Hshimoto, T. and Aoki, T. Evolutionary implications of the mosaic pyrimidine-biosynthetic pathway in eukaryotes. Gene 257 (2000) 209–222. [DOI] [PMID: 11080587]
[EC created 1983 as EC, transferred 2009 to EC, modified 2011]

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