4-Oxalocrotonate tautomerase

4-oxalocrotonate tautomerase

Identifiers

Symbol

Taut

Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe; PDBj
PDBsum	structure summary

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, o-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.^[3] This enzyme is also unusual in that it uses a proline residue at the amino terminus as an active site residue.

References

↑ 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.
↑ 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.
↑ Subramanya HS, Roper DI, Dauter Z, Dodson EJ, Davies GJ, Wilson KS, Wigley DB. Enzymatic ketonization of 2-hydroxymuconate: specificity and mechanism investigated by the crystal structures of two isomerases. (1996) Biochemistry. 35(3):792-802. PMID 8547259

Isomerases: intramolecular oxidoreductases (EC 5.3)

5.3.1: Aldoses/Ketoses	Triosephosphate isomerase Ribose-5-phosphate isomerase Mannose phosphate isomerase Glucose isomerase

5.3.2: Keto/Enol	Phenylpyruvate tautomerase Oxaloacetate tautomerase

5.3.3: C = C	Steroid D-isomerase Isopentenyl-diphosphate delta isomerase Vinylacetyl-CoA D-isomerase Muconolactone D-isomerase Cholestenol Delta-isomerase (EBP) Methylitaconate D-isomerase Aconitate Delta-isomerase Enoyl CoA isomerase Prostaglandin-A1 Delta-isomerase 5-carboxymethyl-2-hydroxymuconate D-isomerase Isopiperitenone D-isomerase L-dopachrome isomerase Polyenoic fatty acid isomerase

5.3.4: S-S	Protein disulfide-isomerase (PDIA3)

5.3.99: other	Prostaglandin D2 synthase/Prostaglandin-D synthase Prostaglandin E synthase Prostacyclin synthase Thromboxane-A synthase

Proteins: enzymes

Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis Enzyme kinetics Lineweaver–Burk plot Michaelis–Menten kinetics

Regulation	Allosteric regulation Cooperativity Enzyme inhibitor

Classification	EC number Enzyme superfamily Enzyme family List of enzymes

Types	EC1 Oxidoreductases(list) EC2 Transferases(list) EC3 Hydrolases(list) EC4 Lyases(list) EC5 Isomerases(list) EC6 Ligases(list)

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