title: Alternate substrates and inhibitors of bacterial 4-hydroxyphenylpyruvate dioxygenase.
abstract: A variety of analogues of (4-hydroxyphenyl)pyruvic acid were synthesized, and the reactions of these compounds with the 4-hydroxyphenylpyruvate dioxygenase from Pseudomonas sp. P.J. 874 were examined. Several of the ring-substituted substrate analogues are reversible inhibitors of the enzyme, the most potent being the competitive inhibitor (2,6-difluoro-4-hydroxyphenyl) pyruvate (Ki = 1.3 microM). Two substrate analogues (2-fluoro-4-hydroxyphenyl)pyruvate and [(4-hydroxyphenyl)thio]pyruvate proved to be alternate substrates for the enzyme. The former compound is converted to (3-fluoro-2,5-dihydroxyphenyl)acetate in an essentially normal catalytic sequence including oxidative decarboxylation, ring hydroxylation, and side-chain migration. The latter compound, however, undergoes oxidative decarboxylation and sulfoxidation to give [(4-hydroxyphenyl)sulfinyl]acetate; ring oxidation is not observed. The implications of these results with regard to the catalytic mechanism of 4-hydroxyphenylpyruvate dioxygenase are discussed.
mesh_terms: D015111:4-Hydroxyphenylpyruvate Dioxygenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D010105:Oxygenases / Q000378:metabolism*; D011549:Pseudomonas / Q000201:enzymology*; D011773:Pyruvates / Q000138:chemical synthesis
chemical_list: D011773:Pyruvates; D010105:Oxygenases; D015111:4-Hydroxyphenylpyruvate Dioxygenase