Zheng Yi, Cloutier Pierre, Hunting Darel J, Wagner J Richard, Sanche Léon
Canadian Institutes of Health Research Group in the Radiation Sciences, Faculty of Medicine, University of Sherbrooke, Sherbrooke, QC, Canada J1H 5N4.
J Am Chem Soc. 2004 Feb 4;126(4):1002-3. doi: 10.1021/ja0388562.
Thymidine was exposed to low-energy electrons (LEE) as a thin solid film under a high vacuum. Nonvolatile radiation products, remaining on the irradiated surface, were analyzed by HPLC/UV and GC/MS. Here, we show that exposure of thymidine to 3-100 eV electrons gives thymine as a major product with a yield of 3.2 x 10-2 per electron (about one-third of the total decomposition of thymidine). The formation of thymine indicates that LEE induces cleavage of the glycosidic bond separating the base and sugar moieties, suggesting a nonionizing resonant process involving dissociative attachment (<15 eV). In contrast, this reaction is not very efficient by DNA base ionization and does not occur by the reaction of solvated electrons with DNA. These studies introduce a new mechanism of DNA damage involving the interaction of LEE.
在高真空条件下，胸腺嘧啶核苷以薄固体膜的形式暴露于低能电子（LEE）。通过高效液相色谱/紫外（HPLC/UV）和气相色谱/质谱（GC/MS）分析残留在辐照表面的非挥发性辐射产物。在此，我们表明，胸腺嘧啶核苷暴露于3 - 100电子伏特的电子下会产生胸腺嘧啶作为主要产物，每个电子的产率为3.2×10⁻²（约占胸腺嘧啶核苷总分解量的三分之一）。胸腺嘧啶的形成表明低能电子诱导了分离碱基和糖部分的糖苷键的断裂，这表明存在一个涉及解离附着（<15电子伏特）的非电离共振过程。相比之下，通过DNA碱基电离，该反应效率不高，并且溶剂化电子与DNA的反应不会发生。这些研究引入了一种涉及低能电子相互作用的DNA损伤新机制。
