Near edge X-ray absorption fine structure of DNA thin film irradiated with soft X-rays

軟X線照射したDNA薄膜のX線吸収端近傍微細構造スペクトル

藤井 健太郎; 横谷 明徳

Fujii, Kentaro; Yokoya, Akinari

軟X線を照射したDNAの分子変化について調べるため、単色軟X線を照射したDNA薄膜のX線吸収端近傍微細構造スペクトルを観測した。その結果、照射した試料中に生成した最終生成物の分子構造を反映したスペクトルを観測することに成功した。得られた結果とこれまでにわれわれが行った軟X線によってDNA中に生じる主鎖切断や塩基損傷の収率の変化とを相互に比較して、各エネルギーの軟X線照射によって起こる分子変化のメカニズムについて議論する。

To in-vestigate the mechanism of the molecular change in DNA irradiated with the soft X-rays, we have measured the spectra of the near edge X-ray absorption fine structure (NEXAFS) of DNA caused by exposure to monochromatic soft X-rays. We used a calf thymus DNA and oligonucleotide thin films as samples and observed N K-shell and O K-shell NEXAFS spectral changes. The typical monochromatic soft X-ray energies used for the irradiation (380, 435, 560, and 760 eV) were obtained from SPring-8, BL23SU. The observed spectra showed that initiation of the new products by the irradiation in the irradiated sample and the dissociation of molecular structure of the DNA by the irradiation. By comparison of these NEXAFS spectral changes with the yields of base lesions and strand breaks as final products, we will discuss the molecular structure of DNA damage site and the site selectivity of damage induction in DNA by soft X-rays.