5.3.3.18 2-(1,2-epoxy-1,2-dihydrophenyl)acetyl-CoA - 422372 5.3.3.18 2-(1,2-epoxy-1,2-dihydrophenyl)acetyl-CoA enzyme acts as a ring 1,2-epoxyphenylacetyl-CoA isomerase forming oxepin-CoA. It mediates the formation and stabilization of the enolate form by abstracting a proton from the side chain at C2 of ring 1,2-epoxyphenylacetyl-CoA. Addition of the abstracted proton to C8, which becomes C4, of the ring leads to a rearrangement of the double bonds and results in a C-C cleavage of the two epoxy-C-O bonds, yielding the oxepin 422372 5.3.3.18 additional information enzyme may undergo isomerization or a ring-opening reaction via a Delta3,Delta2-enoyl-CoA isomerase-like mechanism 89