5.3.2.6 evolution 4-oxalocrotonate tautomerase is a member of the tautomerase superfamily 720309 5.3.2.6 evolution mechanism and the evolution of 4-oxalocrotonate tautomerase, and 5-(carboxymethyl)-2-hydroxymuconate isomerase, EC 5.3.3.10, and their respective pathways, overview -, 719634 5.3.2.6 evolution mechanism and the evolution of 4-oxalocrotonate tautomerase, EC 5.3.2.6, and 5-(carboxymethyl)-2-hydroxymuconate isomerase and their respective pathways, overview -, 719634 5.3.2.6 evolution the enzyme is a member of the tautomerase superfamily -, 718874 5.3.2.6 malfunction covalent modification of Pro-1 by 3-bromopropiolate inactivates YwhB, implicating Pro-1 as a critical catalytic residue in the conversion of phenylenolpyruvate to phenylpyruvate 718847 5.3.2.6 malfunction introduction of polar residues into the active site produces significant decreases in kcat and Km -, 718844 5.3.2.6 malfunction modification by 3-bromopyruvate of three active sites per hexamer abolishes essentially all activity of the hexamer, spectrocopic and sequence analysis of labeled peptides, overview -, 718826 5.3.2.6 metabolism 4-oxalocrotonate tautomerase is an essential enzyme in the degradative metabolism pathway occurring in the Krebs cycle 720309 5.3.2.6 metabolism 4-oxalocrotonate tautomerase is part of a set of inducible enzymes that converts aromatic hydrocarbons to intermediates in the Krebs cycle -, 719636 5.3.2.6 metabolism in the catechol meta-fission pathway elaborated by Pseudomonas putida mt-2 ketonization of 2-hydroxymuconate by 4-oxalocrotonate tautomerase generates the alpha,beta-unsaturated ketone 2-oxo-3-(E)-hexenedioate, which undergoes decarboxylation and further processing to intermediates in the Krebs cycle -, 719634 5.3.2.6 metabolism in the homoprotocatechuate pathway elaborated by Escherichia coli C ketonization of 5-(carboxymethyl)-2-hydroxymuconate by 5-(carboxymethyl)-2-hydroxymuconate isomerase generates the alpha,beta-unsaturated ketone, which undergoes decarboxylation and further processing to intermediates in the Krebs cycle -, 719634 5.3.2.6 metabolism the enzyme is involved in the degradation of 4-hydroxybenzoate via the protocatechuate 2,3-cleavage pathway, overview 704310 5.3.2.6 metabolism the enzyme is part of a degradative pathway that converts various aromatic hydrocarbons to intermediates in the Krebs cycle -, 718830 5.3.2.6 additional information immediate nonenzymatic conversion of 2-oxo-3-hexenedioate to 2-hydroxy-3-trans-hexenedioate with NaBH4. Rate constants for the nonenzymatic phosphate-catalyzed ketonization of 2-hydroxymuconate, overview -, 719633 5.3.2.6 additional information structure-function relationship and kinetic analysis, detailed overview 718840 5.3.2.6 additional information structure-function relationship, spectroscopic NMR analysis, detailed overview. Three arginine residues, Arg11, Arg39, and Arg61, are localized in the active site of 4-oxalocrotonate tautomerase. Importance of Arg11 in properly orienting the dicarboxylate substrate by interacting with the charged 6-carboxylate group. Arg39 interacts with the 1-carboxylate and the 2-keto group of the substrate to promote carbonyl polarization and catalysis, while Pro-1 transfers protons from C-3 to C-5. Arg61 does not play a significant role in either substrate binding or catalysis -, 718830 5.3.2.6 additional information the fully functional enzyme requires both subunits, active site structure and function of hh4-OT, overview. Three type II sites are formed at the other end of the heterodimeric unit interface around betaPro-1. As with the type I sites, two of the type II active site sides are composed of loops, but these loops are contributed from different subunits, that is, the alphaA'beta2' loop in the beta-subunit and the beta1alphaA loop in the alpha-subunit. The third side of the type II active site is composed of the intramonomeric alpha-subunit beta2-beta3 loop instead of a 310 helix -, 718874 5.3.2.6 physiological function 4-OT catalyzes the ketonization process of 2-oxo-4-hexenedioate to its conjugated isomer, 2-oxo-3-hexadienedioate, through the dienol intermediate 2-hydroxymuconate. This proton transfer process is an essential part of degradative metabolism pathway to convert various aromatic hydrocarbons into their corresponding intermediates in the Krebs cycle 720309 5.3.2.6 physiological function 4-oxalocrotonate tautomerase is an extremely efficient catalyst apparently processing either isomer near the diffusion control limit of a small molecule and an enzyme -, 719633 5.3.2.6 physiological function 4-oxalocrotonate tautomerase isozymes play prominent roles in the bacterial utilization of aromatic hydrocarbons as sole carbon sources -, 718874