Oxidation of phenols by chloroperoxidase

Carmichael, Robert D.; Fedorak, Phillip M.; Pickard, Michael A.

doi:10.1007/bf01042380

Cited by 36 publications

(18 citation statements)

References 14 publications

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“…Assumption 2 was required to provide the mathematical link between each substrate and the one substrate, tmp, that does not react directly with the enzyme (1,20). Since f psE compares the reaction of Scheme II, step 7, with the sum of steps 7 and 9, it depends only upon the concentrations of the organic substrate and chloride.…”

Section: Direct Chlorine Transfer In Chloroperoxidase Reactionsmentioning

confidence: 99%

Quantitating Direct Chlorine Transfer from Enzyme to Substrate in Chloroperoxidase-catalyzed Reactions

Libby

Beachy

Phipps

1996

Journal of Biological Chemistry

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Substrate competition methods that were previously used to quantitate the involvement of free Cl 2 in the chloride-dependent peroxidatic reactions catalyzed by chloroperoxidase (CPO) (Libby, R. D., Shedd, A. L., Phipps, K. A., Beachy, T. M., and Gerstberger, S. M., (1992) J. Biol. Chem. 267, 1769 -1775) are extended to CPO-catalyzed halogenation reactions. Relative substrate specificities of halogen acceptor substrates (RHs) antipyrine (ap), NADH, 2-chlorodimedone (2cd), and barbituric acid (ba) are compared with previously studied peroxidatic substrates catechol (cat) and 2,4,6-trimethylphenol (tmp) in their reactions with the CPO-H 2 O 2 -Cl system versus the hypochlorite-Cl system. Studies were carried out at pH 2.75 over a chloride concentration range of 1-100 mM and at pH 4.80 over a chloride concentration range of 100 -400 mM. Competition studies involved successive pairwise comparisons of substrates of increasing enzyme specificity. The orders of specificities, ba > 2cd > ap > cat > tmp at pH 2.75 and ba > 2cd > NADH > ap > cat > tmp at pH 4.80, are the same for both the CPO-H 2 O 2 -Cl and hypochlorite-Cl systems. However, the magnitudes of the specificities are different between the two systems. In all comparisons except ap versus cat, the specificity of the CPO-H 2 O 2 -Cl system toward the preferred substrate is higher than that of the hypochlorite-Cl system. Quantitative comparisons between specificities of CPO-H 2 O 2 -Cl and hypochlorite-Cl systems indicate that at least 98% of the CPO-catalyzed halogenation reactions of ba, 2cd, NADH, and ap occur by mechanisms in which the substrate reacts directly with the enzyme. Thus, less than 2% of any of the CPO reactions could possibly involve a free oxidized halogen intermediate. All data are consistent with a mechanism in which RH binds to the CPO chlorinating intermediate (EOCl), and the chlorine atom is transferred directly from EOCl to RH. Further, the results indicate that any halogenation substrate with a higher CPO specificity than ap must also undergo direct chlorine transfer from the enzyme.These results underscore the critical need for quantitative kinetic evidence in establishing the extent of involvement of any potential reaction intermediate. 269, 7950 -7956).Recently we reported the first direct kinetic evidence for the involvement of a free oxidized chlorine intermediate, Cl 2 , in a reaction catalyzed by chloroperoxidase (chloride:hydrogen peroxide oxidoreductase, EC 1.11.1.10) (1). CPO 1 is a very versatile enzyme. In addition to catalyzing reactions characteristic of peroxidases, hydrogen peroxide-supported oxidation, and iodi-* This work was supported by NIGMS, National Institutes of Health, Grant 7 R15 GM42078-02. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.‡ To whom correspondence should be addressed.1 The abbreviations used are: CPO, chloroperoxidase; t...

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Section: Direct Chlorine Transfer In Chloroperoxidase Reactionsmentioning

confidence: 99%

Quantitating Direct Chlorine Transfer from Enzyme to Substrate in Chloroperoxidase-catalyzed Reactions

Libby

Beachy

Phipps

1996

Journal of Biological Chemistry

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“…The reaction products are mainly quinones and the mechanism involves free radical formation. Chloroperoxidase (CPO) from Caldaryomyces fumago, an enzyme with three different catalytic activities (halogenase, peroxidase and catalase), catalyzes phenol oxidation (Carmichael et al 1985). On the other hand, chloroperoxidase shows close structural (Dawson 1988) and catalytic similarities with the cytochrome P450 (Sundaramoorthy et al 1995).…”

mentioning

confidence: 99%

Determination of Genotoxicity Using a Chloroperoxidase-Mediated Model of PAH-DNA Adduct Formation

Márquez-Rocha

Pica-Granados

Sandoval-Villasana

et al. 1997

Bulletin of Environmental Contamination and Toxicology

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“…In contrast, phenolic compounds specially chlorinated phenols are unusual, being very toxic and caustic, for that reason they are considered highly pollutants (Atlow et al 1984;Carmichael et al 1985). These compounds are present in the wastewaters generated from industrial activities as such petrochemical, coalconversion, pharmaceutical, wood preserving, plastic, rubber proofing, pesticide use, iron steel and paper and cellulose bleaching.…”

mentioning

confidence: 99%

Chloroperoxidase mediated oxidation of chlorinated phenols using electrogenerated hydrogen peroxide

H.¹,

elia²,

Bon³

2007

Electron. J. Biotechnol.

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Oxidation of phenols by chloroperoxidase

Cited by 36 publications

References 14 publications

Quantitating Direct Chlorine Transfer from Enzyme to Substrate in Chloroperoxidase-catalyzed Reactions

Quantitating Direct Chlorine Transfer from Enzyme to Substrate in Chloroperoxidase-catalyzed Reactions

Determination of Genotoxicity Using a Chloroperoxidase-Mediated Model of PAH-DNA Adduct Formation

Chloroperoxidase mediated oxidation of chlorinated phenols using electrogenerated hydrogen peroxide

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