[52] Antimicrobial activity of myeloperoxidase

Klebanoff, Seymour J.; Waltersdorph, A M; Rosen, Henry

doi:10.1016/s0076-6879(84)05055-2

Cited by 215 publications

(136 citation statements)

References 20 publications

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“…MPO from human leukocytes was purchased from Alexis Biochemicals and had an RZ (A 430/A280) Ն 0.75. MPO concentration and activity was determined spectrophotometrically ( 430 ϭ 8.9 ϫ 10 4 M Ϫ1 cm Ϫ1 per heme) (37) and by the guaiacol oxidation assay (38), respectively. HRP was obtained from Sigma, and its concentration was determined spectrophotometrically ( 401 ϭ 1.02 ϫ 10 5 M Ϫ1 cm Ϫ1 ) (39).…”

Section: Methodsmentioning

confidence: 99%

Inhibition of myeloperoxidase-mediated protein nitration by tempol: Kinetics, mechanism, and implications

Vaz

Augusto

2008

Proc. Natl. Acad. Sci. U.S.A.

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Despite the therapeutic potential of tempol (4-hydroxy-2,2,6,6-tetra-methyl-1-piperidinyloxy) and related nitroxides as antioxidants, their effects on peroxidase-mediated protein tyrosine nitration remain unexplored. This posttranslational protein modification is a biomarker of nitric oxide-derived oxidants, and, relevantly, it parallels tissue injury in animal models of inflammation and is attenuated by tempol treatment. Here, we examine tempol effects on ribonuclease (RNase) nitration mediated by myeloperoxidase (MPO), a mammalian enzyme that plays a central role in various inflammatory processes. Some experiments were also performed with horseradish peroxidase (HRP). We show that tempol efficiently inhibits peroxidase-mediated RNase nitration. For instance, 10 M tempol was able to inhibit by 90% the yield of 290 M 3-nitrotyrosine produced from 370 M RNase. The effect of tempol was not completely catalytic because part of it was consumed by recombination with RNase-tyrosyl radicals. The second-order rate constant of the reaction of tempol with MPO compound I and II were determined by stopped-flow kinetics as 3.3 ؋ 10 6 and 2.6 ؋ 10 4 M ؊1 s ؊1 , respectively (pH 7.4, 25°C); the corresponding HRP constants were orders of magnitude smaller. Time-dependent hydrogen peroxide and nitrite consumption and oxygen production in the incubations were quantified experimentally and modeled by kinetic simulations. The results indicate that tempol inhibits peroxidase-mediated RNase nitration mainly because of its reaction with nitrogen dioxide to produce the oxammonium cation, which, in turn, recycles back to tempol by reacting with hydrogen peroxide and superoxide radical to produce oxygen and regenerate nitrite. The implications for nitroxide antioxidant mechanisms are discussed.antioxidant ͉ tyrosine ͉ tyrosine nitration ͉ nitroxides ͉ nitric oxide-derived oxidants

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Section: Methodsmentioning

confidence: 99%

Inhibition of myeloperoxidase-mediated protein nitration by tempol: Kinetics, mechanism, and implications

Vaz

Augusto

2008

Proc. Natl. Acad. Sci. U.S.A.

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“…Materials-Porcine eosinophil peroxidase (EPO) 1 was isolated according to the method of Jorg (27) employing guaiacol oxidation as the assay (28). The purity of EPO preparations was assured before use by demonstrating an RZ of 0.9 (A415/A280), SDS-polyacrylamide gel electrophoresis analysis with Coomassie Blue staining, and in-gel tetramethylbenzidine peroxidase staining to confirm no contaminating myeloperoxidase activity (29).…”

Section: Methodsmentioning

confidence: 99%

Eosinophil Peroxidase-derived Reactive Brominating Species Target the Vinyl Ether Bond of Plasmalogens Generating a Novel Chemoattractant, α-Bromo Fatty Aldehyde

Albert¹,

Thukkani²,

Heuertz³

et al. 2003

Journal of Biological Chemistry

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Plasmalogens are a subclass of glycerophospholipids that are enriched in the plasma membrane of many mammalian cells. The vinyl ether bond of plasmalogens renders them susceptible to oxidation. Accordingly, it was hypothesized that reactive brominating species, a unique oxidant formed at the sites of eosinophil activation, such as in asthma, might selectively target plasmalogens for oxidation. Here we show that reactive brominating species produced by the eosinophil peroxidase system of activated eosinophils attack the vinyl ether bond of plasmalogens. Reactive brominating species produced by eosinophil peroxidase target the vinyl ether bond of plasmalogens resulting in the production of a neutral lipid and lysophosphatidylcholine. Chromatographic and mass spectrometric analyses of this neutral lipid demonstrated that it was 2-bromohexadecanal (2-BrHDA). Reactive brominating species produced by eosinophil peroxidase attacked the plasmalogen vinyl ether bond at acidic pH. Bromide was the preferred substrate for eosinophil peroxidase, and chloride was not appreciably used even at a 1000-fold molar excess. Furthermore, 2-BrHDA production elicited by eosinophil peroxidase-derived reactive brominating species in the presence of 100 M NaBr doubled with the addition of 100 mM NaCl. The potential physiological significance of this pathway was suggested by the demonstration that 2-BrHDA was produced by phorbol myristate acetate-stimulated eosinophils and by the demonstration that 2-BrHDA is a phagocyte chemoattractant. Taken together, the present studies demonstrate the targeting of the vinyl ether bond of plasmalogens by the reactive brominating species produced by eosinophil peroxidase and by activated eosinophils, resulting in the production of brominated fatty aldehydes.

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“…Hypochlorous acid is generated from chloride ions (Cl Ϫ ) and H 2 O 2 by the heme enzyme myeloperoxidase (8 -10). A prominent role for myeloperoxidase in bacterial killing has been proposed (11)(12)(13)(14)(15)(16) and confirmed in vivo involving a mouse model of polymicrobial sepsis (17). Aberrant Hsp60 may also play a role during inflammation of human tissue.…”

mentioning

confidence: 86%

Potential Role of Methionine Sulfoxide in the Inactivation of the Chaperone GroEL by Hypochlorous Acid (HOCl) and Peroxynitrite (ONOO–)

Khor

Fisher

Schöneich

2004

Journal of Biological Chemistry

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GroEL is an Escherichia coli molecular chaperone that functions in vivo to fold newly synthesized polypeptides as well as to bind and refold denatured proteins during stress. This protein is a suitable model for its eukaryotic homolog, heat shock protein 60 (Hsp60), due to the high number of conserved amino acid sequences and similar function. Here, we will provide evidence that GroEL is rather insensitive to oxidants produced endogenously during metabolism, such as nitric oxide ( ⅐ NO) or hydrogen peroxide (H 2 O 2 ), but is efficiently modified and inactivated by reactive species generated by phagocytes, such as peroxynitrite (ONOO ؊ ) and hypochlorous acid (HOCl). For the exposure of 17.5 M GroEL to 100 -250 M HOCl, the major pathway of inactivation was through the oxidation of methionine to methionine sulfoxide, established through mass spectrometric detection of methionine sulfoxide and the reactivation of a significant fraction of inactivated GroEL by the enzyme methionine sulfoxide reductase B/A (MsrB/A). In addition to the oxidation of methionine, HOCl caused the conversion of cysteine to cysteic acid and this product may account for the remainder of inactivated GroEL not recoverable through MsrB/A. In contrast, HOCl produced only negligible yields of 3-chlorotyrosine. A remarkable finding was the conversion of Met 111 and Met 114 to Met sulfone, which suggests a rather low reduction potential of these 2 residues in GroEL. The high sensitivity of GroEL toward HOCl and ONOO ؊ suggests that this protein may be a target for bacterial killing by phagocytes.GroEL and its eukaryotic analog, heat shock protein 60 (Hsp60), 1 are highly sequence-related members of the Group I subclass of chaperonin 60 (Cpn60) (1). These proteins assist the folding of newly synthesized polypeptides (GroEL) or translocated preproteins (mitochondrial Hsp60). The functional unit of GroEL (and of most Cpn60 proteins) is a sandwich of two heptameric rings, which are stacked end to end. Depending on the protein substrate, different ligands such as K ϩ , Mg 2ϩ , ATP, and the cofactor GroES (or Hsp10) may be required for proper folding. Following the trapping of an unfolded or misfolded protein substrate in the hydrophobic interior of GroEL, the binding of ATP and GroES causes a conformational transition, which changes the interior surface properties from hydrophobic to hydrophilic, thus triggering protein folding (1, 2). Mammalian Hsp60 differs from GroEL in that it forms stable and functional heptameric rings in the absence of ATP and its cofactor Hsp10 (3). Our rationale for investigating the oxidative inactivation of GroEL is 2-fold: (i) its potential involvement in bacterial killing by phagocytes and (ii) a potential role for its analog, Hsp60, in an inflammatory and proapoptotic response during cardiovascular disease, as described below.Hsp60 proteins play an important role in the cellular protection against oxidative stress (4, 5). Studies with mutant strains of Saccharomyces cerevisiae exposed to various oxidants show that a decre...

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[52] Antimicrobial activity of myeloperoxidase

Cited by 215 publications

References 20 publications

Inhibition of myeloperoxidase-mediated protein nitration by tempol: Kinetics, mechanism, and implications

Inhibition of myeloperoxidase-mediated protein nitration by tempol: Kinetics, mechanism, and implications

Eosinophil Peroxidase-derived Reactive Brominating Species Target the Vinyl Ether Bond of Plasmalogens Generating a Novel Chemoattractant, α-Bromo Fatty Aldehyde

Potential Role of Methionine Sulfoxide in the Inactivation of the Chaperone GroEL by Hypochlorous Acid (HOCl) and Peroxynitrite (ONOO–)

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