Conserved Site

Enoyl-CoA hydratase/isomerase, conserved site (IPR018376)

Short name: Enoyl-CoA_hyd/isom_CS


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 [PMID: 11263873]. 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 [PMID: 17198383]. Enzymes in the crotonase superfamily include:

  • Enoyl-CoA hydratase (crotonase; EC:, which catalyses the hydratation of 2-trans-enoyl-CoA into 3-hydroxyacyl-CoA [PMID: 12445775].
  • 3-2trans-enoyl-CoA isomerase (or dodecenoyl-CoA isomerise; EC:, which shifts the 3-double bond of the intermediates of unsaturated fatty acid oxidation to the 2-trans position [PMID: 1958319].
  • 3-hydroxbutyryl-CoA dehydratase (crotonase; EC:, a bacterial enzyme involved in the butyrate/butanol-producing pathway.
  • 4-Chlorobenzoyl-CoA dehalogenase (EC:, a Pseudomonas enzyme which catalyses the conversion of 4-chlorobenzoate-CoA to 4-hydroxybenzoate-CoA [PMID: 8679561].
  • Dienoyl-CoA isomerise, which catalyses the isomerisation of 3-trans,5-cis-dienoyl-CoA to 2-trans,4-trans-dienoyl-CoA [PMID: 9739087].
  • Naphthoate synthase (MenB, or DHNA synthetase; EC:, a bacterial enzyme involved in the biosynthesis of menaquinone (vitamin K2) [PMID: 16131752].
  • Carnitine racemase (gene caiD), which catalyses the reversible conversion of crotonobetaine to L-carnitine in Escherichia coli [PMID: 11551212].
  • Methylmalonyl CoA decarboxylase (MMCD; EC:, which has a hexameric structure (dimer of trimers) [PMID: 10769118].
  • Carboxymethylproline synthase (CarB), which is involved in carbapenem biosynthesis [PMID: 16096274].
  • 6-oxo camphor hydrolase, which catalyses the desymmetrisation of bicyclic beta-diketones to optically active keto acids [PMID: 15138275].
  • The alpha subunit of fatty oxidation complex, a multi-enzyme complex that catalyses the last three reactions in the fatty acid beta-oxidation cycle [PMID: 5229654].
  • AUH protein, a bifunctional RNA-binding homologue of enoyl-CoA hydratase [PMID: 11738050].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0003824 catalytic activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns