Variation in DNA damage induced by monochromatic soft X-rays in the energy region of oxygen K-edge

Sugaya, Yuki ; Shiina, Takuya; Shiraishi, Iyo; Fujii, Kentaro; Yokoya, Akinari

In this study, we aim to reveal the role of direct ionization at the energy region of oxygen K-edge in the selective DNA damage. We measure the yields of single strand breaks (SSBs), base lesions, and AP sites produced in thin film of pUC18 plasmid DNA by irradiation of several soft X-rays which excite a1s electron to anti-bonding energy states or a vacuum level. The yields of base lesions and AP sites are determined by post-irradiation-treatment of the DNA with enzymatic probes, which excise (Nth and Fpg for pyrimidine and purine base lesion, respectively, and Nfo for AP site) and convert the lesions into detectable SSBs. The obtained data will be compared with our previous data obtained by soft X-ray irradiation around carbon and nitrogen K-edge region.