Enzyme

5.3.3.8 - Delta(3)-Delta(2)-enoyl-CoA isomerase

Alternative Name(s)
  • Dodecenoyl-CoA isomerase.
  • Dodecenoyl-CoA Delta-isomerase.
  • Delta(3),Delta(2)-enoyl-CoA isomerase.
  • Acetylene-allene isomerase.
  • Delta(3)-cis-Delta(2)-trans-enoyl-CoA isomerase.
  • 3,2-trans-enoyl-CoA isomerase.

Catalytic Activity

(3E)-enoyl-CoA = a 4-saturated (2E)-enoyl-CoA

Cofactors

There are no Cofactors for this Enzyme

Reaction Mechanisms

    3,2-trans-enoyl-CoA isomerase (mitochondrial) By Reference

    Delta3-delta2-enoyl CoA isomerase (enoyl-CoA isomerase) is a mitochondrial enzyme, in this case from human, catalyses the conversion of 3-cis-enoyl-CoA or 3-trans-enoyl-CoA into 2-trans-enoyl-CoA. This is involved in an auxiliary pathway of fatty acid degradation, and the product is subsequently metabolised further by other enzymes of the pathway.

    Enoyl-CoA isomerases use fatty acyl substrates with side-chains ranging from C6 to C16. The reaction used as example uses a C12 compund as substrate

    This reaction proceeds via an E1cb mechanism in which Glu136 deprotonates the C2 atom of the substrate, forming the conjugate base. The thioester oxygen atom holds the negative charge, and is stabilised by the presence of an oxyanion hole formed by the amide groups of Leu77 and Gly111. As the carbonyl is reformed, the C4 atom of the product is protonated by Glu136.
    Catalytic Residues
    AA Uniprot Uniprot Resid PDB PDB Resid
    Leu P42126 108 1sg4 66
    Gly P42126 153 1sg4 111
    Glu P42126 178 1sg4 136
    Asn P42126 177 1sg4 135
    Step Components

    assisted keto-enol tautomerisation, native state of enzyme regenerated, proton transfer

    Step 1.

    Glu136A deprotonates the substrate with concomitant tautomerisation to the enolate form, which is stabilised by an oxyanion hole composed of the main chain amides of Leu66A and Gly111A

    Step 2.

    The oxyanion intermediate tautomerises to give product with the help of a proton donated by Glu136

    Products.

    The products of the reaction.

Reaction Parameters

  • Kinetic Parameters
    Organism KM Value [mM] Substrate Comment
    Homo sapiens 150 3-trans-hexenoyl-CoA full length enzyme, at pH 8.5 and 25°C
    Saccharomyces cerevisiae 20000 3-trans-hexenoyl-CoA wild type enzyme, at pH 8.5 and 25°C
  • Temperature

    There are no reaction parameters information for this Enzyme.

  • pH
    Organism pH Range Comment
    Bos taurus 5 - 9 pH 5: about 50% of maximal activity, pH 7-9: maximal activity
    Rattus norvegicus 6 - 8.5 at least 60% of maximal activity over the pH range 6 to 8.5

Associated Proteins

Protein name Organism
Enoyl-CoA delta isomerase 1, peroxisomal Mouse-ear cress
Enoyl-CoA delta isomerase 3, peroxisomal Mouse
Enoyl-CoA delta isomerase 1, mitochondrial Human
Enoyl-CoA delta isomerase 3 Mouse-ear cress
Enoyl-CoA delta isomerase 2, peroxisomal Mouse-ear cress

Citations

There are no citations for this Enzyme