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The pH-rate profiles for the kinetic parameters of 4-oxalocrotonate tautomerase (4-OT) have been measured using 2-hydroxy-2,4-hexadiendioate (2a) and 2-hydroxy-2,4-pentadienoate (2b) as substrates. The pH dependences of log (kcat/Km) and of log kcat for the slow, nonsticky substrate 2b, which lacks a 6-carboxyl group, were bell-shaped with limiting slopes(More)
4-Oxalocrotonate tautomerase (EC 5.3.2-; 4-OT), a hexamer consisting of 62 residues per subunit, catalyzes the isomerization of unsaturated alpha-keto acids, converting unconjugated ketones to the conjugated isomers via a dienolic intermediate. The recently solved crystal structure of an isozyme of 4-OT suggests that the amino-terminal proline is the(More)
The xylH gene encoding 4-oxalocrotonate tautomerase (4-OT) has been located on a subclone of the Pseudomonas putida mt-2 TOL plasmid pWW0 and inserted into an Escherichia coli expression vector. Several of the genes of the metafission pathway encoded by pWW0 have been cloned in E. coli, but the overexpression of their gene products has met with limited(More)
The reaction catalyzed by the thiamin-diphosphate-dependent yeast pyruvate decarboxylase, which is hysteretically regulated by pyruvate, undergoes paracatalytic oxidative diversion by 2,6-dichlorophenolindophenol, which traps a carbanionic intermediate and diverts the product from acetaldehyde to acetate (Christen, P. Meth. Enzymol. 1977, 46, 48). This(More)
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