4-Oxalocrotonate tautomerase

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4-Oxalocrotonate tautomerase (EC 5.3.2.-4-OT) is an enzyme that converts 2-hydroxymuconate to the αβ-unsaturated ketone, 2-oxo-3-hexenedioate.[1] This enzyme forms part of a bacterial metabolic pathway that oxidatively catabolizes toluene, p-xylene, 3-ethyltoluene, and 1,2,4-trimethylbenzene into intermediates of the citric acid cycle. With a monomer size of just 62 amino acid residues, the 4-Oxalocrotonate tautomerase is one of the smallest enzyme subunits known.[2] However, in solution the enzyme forms a hexamer of six identical subunits, so the active site may be formed by amino acid residues from several subunits. This enzyme is also unusual in that it uses a proline residue at the amino terminus as an active site residue.

[edit] References

  1. ^ Chen LH, Kenyon GL, Curtin F, Harayama S, Bembenek ME, Hajipour G, Whitman CP (1992). "4-Oxalocrotonate tautomerase, an enzyme composed of 62 amino acid residues per monomer". J. Biol. Chem. 267 (25): 17716–21. PMID 1339435. 
  2. ^ Whitman CP (2002). "The 4-oxalocrotonate tautomerase family of enzymes: how nature makes new enzymes using a beta-alpha-beta structural motif". Arch. Biochem. Biophys. 402 (1): 1–13. doi:10.1016/S0003-9861(02)00052-8. PMID 12051677. 
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