| Type: | Domain | Name: | Crontonase, C-terminal |
| Description: | The crotonase superfamily is comprised of 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 stabilise 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 isomerise, 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 desymmetrisation of bicyclic beta-diketones to optically active keto acids [].The alpha subunit of fatty 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 [].This entry represents the C-terminal domain found in some, but not all, crotonase superfamily members. This domain has an alpha-helical structure, and may be involved in trimerisation. | Short Name: | Crontonase_C |
