4-Oxalocrotonate Tautomerase: Catalyzes the isomerization of unsaturated ketones. The structure is a homohexamer that is arranged as a trimer of dimers. The hexamer contains six active sites, each formed by residues from three monomers, two from one dimer and the third from a neighboring monomer. Each monomer is a beta-alpha-beta fold with two small beta strands at the C-terminus that fold back on themselves. A pair of monomers form a dimer with two-fold symmetry, consisting of a 4-stranded beta sheet with two helices on one side and two additional small beta strands at each end. The dimers are assembled around a 3-fold axis of rotation to form a hexamer, with the short beta strands from each dimer contacting the neighboring dimers.
Jiyao W et al.(2023). "The conserved domain database in 2023.",