Mechanism of inactivation of myeloperoxidase by 4-aminobenzoic acid hydrazide

Kettle, Anthony J.; Gedye, Craig; Winterbourn, Christine C.

doi:10.1042/bj3210503

Cited by 220 publications

(197 citation statements)

References 34 publications

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“…ABAH (42) and azide (43) are both inhibitors of MPO, and both attenuated DMPO-MPO adduct formation. Ascorbate is a substrate and also a reductant in that MPO/H 2 O 2 can oxidize ascorbate, but, perhaps more importantly, ascorbate can rapidly reduce many radical intermediates formed by peroxidases (44).…”

Section: Discussionmentioning

confidence: 99%

Aminoglutethimide-Induced Protein Free Radical Formation on Myeloperoxidase: A Potential Mechanism of Agranulocytosis

Siraki

Jiang

Ehrenshaft

et al. 2007

Chem. Res. Toxicol.

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Aminoglutethimide (AG) is a first-generation aromatase inhibitor used for estrogen-dependent breast cancer. Unfortunately, its use has also been associated with agranulocytosis. We have investigated the metabolism of AG by myeloperoxidase (MPO) and the formation of an MPO protein free radical. We hypothesized that AG oxidation by MPO/H 2 O 2 would produce an AG cation radical that, in the absence of a biochemical reductant, would lead to the oxidation of MPO. We utilized a novel anti-DMPO antibody to detect DMPO (5,5-dimethyl-1-pyrroline N-oxide) covalently bound to protein, which forms only by the reaction of DMPO with a protein free radical. We found that AG metabolism by MPO/H 2 O 2 induced the formation of DMPO-MPO, which was inhibited by MPO inhibitors and ascorbate. Glutethimide, a congener of AG that lacks the aromatic amine, did not cause DMPO-MPO formation, indicating the necessity of oxidation of the aniline moiety in AG. When analyzed by electron spin resonance spectroscopy, we detected a phenyl radical adduct, derived from AG, which may be involved in the free radical formation on MPO. Furthermore, we also found protein-DMPO adducts in MPO-containing, intact human promyelocytic leukemia cells (HL-60). MPO was affinity-purified from HL-60 cells treated with AG/H 2 O 2 and was found to contain DMPO. These findings were also supported by the detection of protein free radicals with electron spin resonance in the cellular cytosolic lysate. The formation of an MPO protein free radical is believed to be mediated by one of two free radical drug metabolites of AG, one of which was characterized by spin trapping with 2-methyl-2-nitrosopropane. These results are the first demonstration of MPO freeradical detection by the anti-DMPO antibody that results from drug oxidation. We propose that drugdependent free radical formation on MPO may play a role in the origin of agranulocytosis.

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Section: Discussionmentioning

confidence: 99%

Aminoglutethimide-Induced Protein Free Radical Formation on Myeloperoxidase: A Potential Mechanism of Agranulocytosis

Siraki

Jiang

Ehrenshaft

et al. 2007

Chem. Res. Toxicol.

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“…ABAH (45) and azide (46) are both inhibitors of MPO, and both attenuated DMPO-MPO adduct formation. Ascorbate is a substrate in that MPO/H 2 O 2 can oxidize ascorbate, but perhaps more importantly, ascorbate can rapidly reduce many radical intermediates formed by peroxidases (47).…”

Section: Discussionmentioning

confidence: 99%

“…As mechanism-based inhibitors of peroxidases have been proposed to form reactive free radical intermediates that bind to the heme active site and inhibit enzyme activity (43)(44)(45)(46), we assayed the remaining peroxidase activity after incubation with PA. However, we found no inhibition of MPO peroxidase activity after treatment with PA (data not shown).…”

Section: Discussionmentioning

confidence: 99%

Procainamide, but notN-Acetylprocainamide, Induces Protein Free Radical Formation on Myeloperoxidase: A Potential Mechanism of Agranulocytosis

Siraki

Deterding

Jiang

et al. 2008

Chem. Res. Toxicol.

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Procainamide (PA) is a drug that is used to treat tachycardia in post-operative patients or for long term maintenance of cardiac arrythmias. Unfortunately, its use has also been associated with agranulocytosis. Here we have investigated the metabolism of PA by myeloperoxidase (MPO) and the formation of an MPO protein free radical. We hypothesized that PA oxidation by MPO/H 2 O 2 would produce a PA cation radical that, in the absence of a biochemical reductant, would lead to the free-radical oxidation of MPO. We utilized a novel anti-DMPO antibody to detect DMPO (5,5-dimethyl-1-pyrroline N-oxide) covalently bound to protein, which forms only by the reaction of DMPO with a protein free radical. We found that PA metabolism by MPO/H 2 O 2 induced the formation of DMPO-MPO, which was inhibited by MPO inhibitors and ascorbate. N-acetyl-PA did not cause DMPO-MPO formation, indicating that the unsubstituted aromatic amine was more oxidizable. PA had a lower calculated ionization potential than N-acetyl-PA. The DMPO adducts of §To whom correspondence should be addressed: Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, 111 TW Alexander Dr., Research Triangle Park, NC USA, 27709. T: (919) 541-5197, F: (919) 541-1043, sirakia@niehs.nih.gov.. Abbreviations: PA, procainamide; NAPA, N-acetyl-procainamide; MPO, myeloperoxidase; ESR, electron spin resonance; DTPA, diethylenetriaminepentaacetic acid; MNP, 2-methyl-2-nitrosopropane; DMPO, 5,5-dimethyl-1-pyrroline N-oxide; ABAH, 4-aminobenzoic acid hydrazide; G/GO,Glucose / glucose oxidase. MPO metabolism, as analyzed by electron spin resonance spectroscopy, included a nitrogen-centered radical and a phenyl radical derived from PA, either of which may be involved in the free radical formation on MPO. Furthermore, we also found protein-DMPO adducts in MPO-containing, intact human promyelocytic leukemia cells . MPO was affinity-purified from HL-60 cells treated with PA/H 2 O 2 and was found to contain DMPO using the anti-DMPO antibody. Mass spectrometry analysis confirmed the identity of the protein as human MPO. These findings were also supported by the detection of protein free radicals with electron spin resonance in the cellular cytosolic lysate. The formation of an MPO protein free radical is believed to be mediated by free radical metabolites of PA, which we characterized by spin trapping. We propose that drug-induced free radical formation on MPO may play a role in the origin of agranulocytosis. NIH Public AccessProcainamide (PA) is a sodium channel blocker which stabilizes electrical conduction in the heart. It is used for treating atrial tachycardia and is specifically recommended for atrial fibrillation of the Wolff-Parkinson-White syndrome (1). Unfortunately, agranulocytosis, an idiosyncratic adverse drug reaction, is associated with the use of procainamide (PA). This condition is characterized by severe neutropenia, where the absolute neutrophil count decreases below 500/uL (2,3), which greatly increases the risk of b...

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“…There has been considerable interest in the development of therapeutically useful MPO inhibitors. A previous study showed that 4-ABAH irreversibly inhibits hypochlorous acid production as a suicide substrate of MPO 7 . A means of monitoring MPO activity under in vivo conditions should help establish the relationship between MPO induction and pathological progression and facilitate preclinical evaluation of MPO inhibitors.…”

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confidence: 99%

Enhanced detection of myeloperoxidase activity in deep tissues through luminescent excitation of near-infrared nanoparticles

Zhang¹,

Francis²,

Prakash

et al. 2013

Nat Med

123

111

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Mechanism of inactivation of myeloperoxidase by 4-aminobenzoic acid hydrazide

Cited by 220 publications

References 34 publications

Aminoglutethimide-Induced Protein Free Radical Formation on Myeloperoxidase: A Potential Mechanism of Agranulocytosis

Aminoglutethimide-Induced Protein Free Radical Formation on Myeloperoxidase: A Potential Mechanism of Agranulocytosis

Procainamide, but notN-Acetylprocainamide, Induces Protein Free Radical Formation on Myeloperoxidase: A Potential Mechanism of Agranulocytosis

Enhanced detection of myeloperoxidase activity in deep tissues through luminescent excitation of near-infrared nanoparticles

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