Peroxyl radicals from tumor promoter organic hydroperoxides induced by human myeloperoxidase and human neutrophils
- National Inst. of Health, Research Triangle Park, NC (United States) Univ. of North Carolina, Chapel Hill (United States)
The decomposition of tumor promotor organic hydroperoxides as catalyzed by human myeloperoxidase (MPO) and human neutrophils (PMN) was investigated by electron paramagnetic resonance. Peroxyl, alkoxyl and carbon-centered free radicals were successfully trapped by spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) for both MPO and PMN systems. The classical peroxidase mechanism is proposed to describe the formation of peroxyl radicals. The authors propose that the tert-butyl peroxyl radical reacts to form tert-butyl alkoxyl radical. {beta}-Scission of tert-butyl alkoxyl radical leads to the formation of methyl radical. In the case of ethyl hydroperoxide, ethyloxyl was not detected with DMPO; rather, {alpha}-hydroxyethyl was trapped by another spin trap, tert-nitrosopropane. The authors propose that ethyloxyl radical rapidly undergoes internal hydrogen atom transfer resulting in the formation of {alpha}-hydroxyethyl radical. The addition of azide (MPO inhibitor) and rabbit antisera IgG fraction for human MPO resulted in the inhibition of free radical formation in both MPO/ and PMN/ organic hydroperoxide systems. The results imply that the MPO of PMN form oxygen-centered free radicals from organic hydroperoxides inside these cells.
- OSTI ID:
- 6006362
- Report Number(s):
- CONF-9104107--
- Journal Information:
- FASEB Journal (Federation of American Societies for Experimental Biology); (United States), Journal Name: FASEB Journal (Federation of American Societies for Experimental Biology); (United States) Vol. 4:3; ISSN FAJOE; ISSN 0892-6638
- Country of Publication:
- United States
- Language:
- English
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560300* -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKOXY RADICALS
ALKYL RADICALS
ANIMALS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
ELECTRON SPIN RESONANCE
ENZYMES
ETHYL RADICALS
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
KINETICS
LEUKOCYTES
MAGNETIC RESONANCE
MAMMALS
MAN
MATERIALS
METHYL RADICALS
NEUTROPHILS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PEROXIDASES
PEROXIDES
PEROXY RADICALS
PRIMATES
PROMOTERS
PROTEINS
RADICALS
REACTION KINETICS
RESONANCE
TUMOR PROMOTERS
VERTEBRATES