Induction of DNA damage, including abasic sites, in plasmid DNA by carbon ion and X-ray irradiation

炭素イオン及びX線照射されたプラスミドDNA中に生じる脱塩基部位を含むDNA損傷

椎名 卓也; 渡辺 立子; 白石 伊世; 鈴木 雅雄*; 菅谷 雄基 ; 藤井 健太郎; 横谷 明徳

Shiina, Takuya; Watanabe, Ritsuko; Shiraishi, Iyo; Suzuki, Masao*; Sugaya, Yuki; Fujii, Kentaro; Yokoya, Akinari

Plasmid DNA was irradiated with carbon ions or X-rays in solutions containing several concentrations of Tris (0.66-200 mM) to determine the yield of abasic (AP) sites and the effect of scavenging capacity. The yield of AP sites, detected as single strand breaks (SSB) after digestion with E. coli endonucrease IV (Nfo), was compared with that of SSB and base lesions. At higher concentrations of Tris, the yields of single or clustered AP sites were significantly lower than those of single or clustered base lesions. The dependence of the yield of AP sites on scavenging capacity was similar to that of prompt strand breaks. These results indicate that the reaction of water radiolysis products, presumably OH radicals, with the sugar-phosphate moieties in the DNA backbone induces both AP sites and SSB with similar efficiency.