Nucleic Acids Research, Vol 26, Issue 15 3599-3607, Copyright © 1998 by Oxford University Press
S Koizume, H Inoue, H Kamiya and E Ohtsuka
We found that single-stranded DNA oligomers containing a 7, 8-dihydro-8-
oxoguanine (8-oxo-G) residue have high reactivity toward KMnO4; the
oxidation of 8-oxo-G induces damage to the neighboring nucleotide residues.
This paper describes the novel reaction in detail, including experiments
that demonstrate the mechanism involved in the induction of DNA damage. The
results using DNAs of various base compositions indicated that damaged G, T
and C (but not A) sites caused strand scissions after hot piperidine
treatment and that the damage around the 8-oxo-G occurred at G sites in
both single and double strands with high frequency. The latter substrates
were less sensitive to damage. Further, kinetic studies of the
KMnO4reaction of single-stranded oligomers suggested that thereactivity of
the DNA bases at the site 5'- adjacent to the 8-oxo-G was in the order G
>A >T, C. This preference correlates with the electron donating
abilities of the bases. In addition, we found that the DNA damage at the G
site, which was connected with the 8-oxo-G by a long abasic chain, was
inhibited in the above order by the addition of dG, dA or dC. On the other
hand, the damage reactions proceeded even after the addition of scavengers
for active oxygen species. This study suggests the involvement of a redox
process in the unique DNA damage initiated by the oxidation of the 8-
oxo-G.
ARTICLES
Neighboring base damage induced by permanganate oxidation of 8- oxoguanine in DNA
Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi- 6, Kita-ku, Sapporo 060-0812, Japan.
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