Biochemical identification of a hydroperoxide derivative of the free 8-oxo-7,8-dihydroguanine base.
Free Radic Biol Med
; 52(4): 749-56, 2012 Feb 15.
Article
em En
| MEDLINE
| ID: mdl-22198182
ABSTRACT
8-Oxo-7,8-dihydroguanine is one the most abundant base lesions in pro- and eukaryotic DNA. In mammalian cells, it is excised by the 8-oxoguanine DNA glycosylase (OGG1) during DNA base-excision repair, and the generated free 8-oxoG base is one of the DNA-derived biomarkers of oxidative stress in biological samples. The modification of 8-oxoG in the context of nucleoside and DNA has been the subject of many studies; however, the oxidative transformation of the free 8-oxoG base has not been described. By using biochemical and cell biological assays, we show that in the presence of molecular oxygen, the free 8-oxoG base transforms to a highly reactive hydroperoxide (8-oxoG*). Specifically, 8-oxoG* oxidizes Amplex red to resorufin, H(2)DCF to DCF, Fe(2+) to Fe(3+), and GSH to GSSG. This property of 8-oxoG* was diminished by treatment with catalase and glutathione peroxidase, but not superoxide dismutase. 8-OxoG* formation was prevented by reducing agents or nitrogen atmosphere. Its addition to CM-H(2)DCF-DA-loaded cells rapidly increased intracellular DCF fluorescence. There were no such properties observed for 8-oxodeoxyguanosine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine, 2'-deoxyguanosine, guanine, adenine, guanosine, and 8-hydroxyadenine. These data imply that a free 8-oxoG base is more susceptible to oxidation than is its nucleoside form and, consequently, it stands as unique among intact and oxidatively modified purines.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Peróxidos
/
Oxidantes
/
Guanina
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
Free Radic Biol Med
Assunto da revista:
BIOQUIMICA
/
MEDICINA
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Estados Unidos