DNA methylation by tert-butyl hydroperoxide-iron (II)

Reduction of tert-butyl hydroperoxide (TBHP) by iron (II) at pH 4.0 or pH 7.0 in the presence of calf thymus DNA led to generation of high yields of methyl radicals and to DNA methylation. Methyl radicals were identified by spin-trapping experiments with 5,5-dimethyl-l-pyrroline N-oxide (DMPO) and α...

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Bibliographic Details
Published in:Free radical biology & medicine 1995-09, Vol.19 (3), p.293-301
Main Authors: Hix, Sonia, Da Silva Morais, Maurício, Augusto, Ohara
Format: Article
Language:English
Subjects:
Alkylation
Animals
C 8-methylguanine
Cattle
Cyclic N-Oxides
DNA - chemistry
DNA alkylation
DNA Damage
DNA methylation
DNA-adducts
Electron Spin Resonance Spectroscopy - methods
Free radicals
Free Radicals - analysis
Hydroperoxides
Iron
Methylation
N 7-methylguanine
Peroxides
Reactive Oxygen Species
Spin Labels
Spin-trapping
tert-Butyl hydroperoxide
tert-Butylhydroperoxide
Thymus Gland
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Summary:Reduction of tert-butyl hydroperoxide (TBHP) by iron (II) at pH 4.0 or pH 7.0 in the presence of calf thymus DNA led to generation of high yields of methyl radicals and to DNA methylation. Methyl radicals were identified by spin-trapping experiments with 5,5-dimethyl-l-pyrroline N-oxide (DMPO) and α-(4-pyridyl-1-oxide)-N- tert-butylnitrone (POBN). The methylated DNA-base adducts were identified in treated DNA hydrolysates by high pressure liquid chromatography (HPLC) and photodiode array UV spectroscopy. In the case of DNA several methylated adducts were identified, namely N 7-methylguanine, C 8-methylguanine, N 3-methyladenine, and O 6-methylguanine. By contrast, 2′-deoxyguanosine is alkylated almost exclusively to C 8-methyl-2′-deoxyguanosine. These results constitute the first evidence that TBHP is able to alkylate DNA.
ISSN:0891-5849
1873-4596
DOI:10.1016/0891-5849(95)00026-T