EC Explorer

1.3.5.2

dihydroorotate dehydrogenase (quinone)

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

dihydroorotate:ubiquinone oxidoreductase, (S)-dihydroorotate:(acceptor) oxidoreductase, (S)-dihydroorotate:acceptor oxidoreductase, DHOdehase (ambiguous), DHOD (ambiguous), DHODase (ambiguous), DHODH

(S)-dihydroorotate:quinone oxidoreductase

59088-23-2

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 1.3.98.1), NAD⁺ (EC 1.3.1.14) or NADP⁺ (EC 1.3.1.15) as electron acceptor.

created 1983 as EC 1.3.99.11, transferred 2009 to EC 1.3.5.2, modified 2011