HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Husain, M. Articles by Chapman, P. J. Search for Related Content PubMed PubMed Citation Articles by Husain, M. Articles by Chapman, P. J. Social Bookmarking                      What's this?

J. Biol. Chem., Vol. 255, Issue 9, 4189-4197, May, 1980

Fluoride elimination from substrates in hydroxylation reactions catalyzed by p-hydroxybenzoate hydroxylase

M Husain, B Entsch, DP Ballou, V Massey and PJ Chapman

Several fluorinated derivatives of p-hydroxybenzoate were synthesized and examined as substrates in the reaction catalyzed by p- hydroxybenzoate hydroxylase. All the derivatives tested served as substrates, undergoing tightly coupled hydroxylation by molecular oxygen. Hydroxylation of the difluoro and tetrafluoro derivatives liberated stoichiometric amounts of fluoride. Little or no fluoride was released with monofluoro substrates. The defluorination caused higher consumption of NADPH with an overall NADPH to oxygen ratio of 2, in contrast to the ratio of 1 with the physiological substrate and with the monofluoro derivatives. Evidence was obtained strongly suggestive of a quinonoid species as the primary product formed upon oxygenative defluorination. The additional equivalent of NADPH consumed upon fluoride elimination is presumably used in a nonenzymatic reaction with the quinonoid intermediate, resulting in the observed dihydroxy product. Stopped flow studies of the reductive and oxidative half- reactions with tetrafluoro-p hydroxybenzoate substrate were examined. The oxygen half-reaction was analogous to that with p-hydroxybenzoate involving two transient oxygenated flavin intermediates. The decay of the first intermediate, a C(4a)-peroxyflavin, results in rupture of the oxygen-oxygen bond and is rate-determining in overall catalysis. This is in contrast to the reaction with the normal substrate, presumably due to a deactivating effect of the fluorine substituents. The above results are consistent with an oxenoid mechanism of oxygen attack.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				F. L. P. Gabriel, M. Cyris, N. Jonkers, W. Giger, K. Guenther, and H.-P. E. Kohler Elucidation of the ipso-Substitution Mechanism for Side-Chain Cleavage of {alpha}-Quaternary 4-Nonylphenols and 4-t-Butoxyphenol in Sphingobium xenophagum Bayram Appl. Envir. Microbiol., May 15, 2007; 73(10): 3320 - 3326. [Abstract] [Full Text] [PDF]

				V. P. Swetha, A. Basu, and P. S. Phale Purification and Characterization of 1-Naphthol-2-Hydroxylase from Carbaryl-Degrading Pseudomonas Strain C4 J. Bacteriol., April 1, 2007; 189(7): 2660 - 2666. [Abstract] [Full Text] [PDF]

				L. Xun and C. M. Webster A Monooxygenase Catalyzes Sequential Dechlorinations of 2,4,6-Trichlorophenol by Oxidative and Hydrolytic Reactions J. Biol. Chem., February 20, 2004; 279(8): 6696 - 6700. [Abstract] [Full Text] [PDF]

				M. R. Gisi and L. Xun Characterization of Chlorophenol 4-Monooxygenase (TftD) and NADH:Flavin Adenine Dinucleotide Oxidoreductase (TftC) of Burkholderia cepacia AC1100 J. Bacteriol., May 1, 2003; 185(9): 2786 - 2792. [Abstract] [Full Text] [PDF]