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8‐Oxoguanine induces intramolecular DNA damage but free 8‐oxoguanine protects intermolecular DNA from oxidative stress
Author(s) -
Kim Ja-Eun,
Choi Seongwon,
Yoo Ju-Ah,
Chung Myung-Hee
Publication year - 2004
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(03)01385-1
Subject(s) - chemistry , dna damage , radical , dna , singlet oxygen , oxidative stress , deoxyguanosine , intramolecular force , dna oxidation , peroxynitrite , reactive oxygen species , photochemistry , biochemistry , stereochemistry , oxygen , superoxide , enzyme , organic chemistry
7,8‐Dihydro‐8‐oxoguanine (8‐oxoguanine; 8‐oxo‐G), one of the major oxidative DNA adducts, is highly susceptible to further oxidation by radicals. We confirmed the higher reactivity of 8‐oxo‐G toward reactive oxygen (singlet oxygen and hydroxyl radical) or nitrogen (peroxynitrite) species as compared to unmodified base. In this study, we raised the question about the effect of this high reactivity toward radicals on intramolecular and intermolecular DNA damage. We found that the amount of intact nucleoside in oligodeoxynucleotide containing 8‐oxo‐G decreased more by various radicals at higher levels of 8‐oxo‐G incorporation, and that the oligodeoxynucleotide damage and plasmid cleavage by hydroxyl radical were inhibited in the presence of 7,8‐dihydro‐8‐oxo‐2′‐deoxyguanosine (8‐oxo‐dG). We conclude that 8‐oxo‐G within DNA induces intramolecular DNA base damage, but that free 8‐oxo‐G protects intermolecular DNA from oxidative stress. These results suggest that 8‐oxo‐G within DNA must be rapidly released to protect DNA from overall oxidative damage.