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The crotonase family comprises mechanistically diverse proteins that share a conserved trimeric quaternary structure (sometimes a hexamer consisting of a dimer of trimers), the core of which consists of 4 turns of a (beta/beta/alpha)n superhelix. Some enzymes in the superfamily have been shown to display dehalogenase, hydratase, and isomerase activities, while others have been implicated in carbon-carbon bond formation and cleavage as well as the hydrolysis of thioesters. However, these different enzymes share the need to stabilize an enolate anion intermediate derived from an acyl-CoA substrate. This is accomplished by two structurally conserved peptidic NH groups that provide hydrogen bonds to the carbonyl moieties of the acyl-CoA substrates and form an "oxyanion hole". The CoA thioester derivatives bind in a characteristic hooked shape and a conserved tunnel binds the pantetheine group of CoA, which links the 3'-phosphate ADP binding site to the site of reaction. Enzymes in the crotonase superfamily include: * Enoyl-CoA hydratase (crotonase; ), which catalyses the hydratation of 2-trans-enoyl-CoA into 3-hydroxyacyl-CoA. * 3-2trans-enoyl-CoA isomerase (or dodecenoyl-CoA isomerise; ), which shifts the 3-double bond of the intermediates of unsaturated fatty acid oxidation to the 2-trans position. * 3-hydroxbutyryl-CoA dehydratase (crotonase; ), a bacterial enzyme involved in the butyrate/butanol-producing pathway. * 4-Chlorobenzoyl-CoA dehalogenase (), a Pseudomonas enzyme which catalyses the conversion of 4-chlorobenzoate-CoA to 4-hydroxybenzoate-CoA. * Dienoyl-CoA isomerase, which catalyses the isomerisation of 3-trans,5-cis-dienoyl-CoA to 2-trans,4-trans-dienoyl-CoA. * Naphthoate synthase (MenB, or DHNA synthetase; ), a bacterial enzyme involved in the biosynthesis of menaquinone (vitamin K2). * Carnitine racemase (gene caiD), which catalyses the reversible conversion of crotonobetaine to L-carnitine in ''Escherichia coli''. * Methylmalonyl CoA decarboxylase (MMCD; ), which has a hexameric structure (dimer of trimers). * Carboxymethylproline synthase (CarB), which is involved in carbapenem biosynthesis. * 6-oxo camphor hydrolase, which catalyses the desymmetrization of bicyclic beta-diketones to optically active keto acids. * The alpha subunit of fatty acid oxidation complex, a multi-enzyme complex that catalyses the last three reactions in the fatty acid beta-oxidation cycle. * AUH protein, a bifunctional RNA-binding homologue of enoyl-CoA hydratase. ==Human proteins containing this domain == AUH; CDY2B; CDYL; CDYL2; DCI; ECH1; ECHDC1; ECHDC2; ECHDC3; ECHS1; EHHADH; HADHA; HCA64; HIBCH; PECI; 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Crotonase family」の詳細全文を読む スポンサード リンク
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