Department of Chemistry-Physical Chemistry, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476, Potsdam-Golm, Germany.
Department 1-Analytical Chemistry and Reference Materials, BAM Federal Institute for Materials Research and Testing, Richard-Willstätter Strasse 11, 12489, Berlin, Germany.
Angew Chem Int Ed Engl. 2017 Aug 28;56(36):10952-10955. doi: 10.1002/anie.201705504. Epub 2017 Jul 28.
Halogenated nucleobases are used as radiosensitizers in cancer radiation therapy, enhancing the reactivity of DNA to secondary low-energy electrons (LEEs). LEEs induce DNA strand breaks at specific energies (resonances) by dissociative electron attachment (DEA). Although halogenated nucleobases show intense DEA resonances at various electron energies in the gas phase, it is inherently difficult to investigate the influence of halogenated nucleobases on the actual DNA strand breakage over the broad range of electron energies at which DEA can take place (<12 eV). By using DNA origami nanostructures, we determined the energy dependence of the strand break cross-section for oligonucleotides modified with 8-bromoadenine ( A). These results were evaluated against DEA measurements with isolated A in the gas phase. Contrary to expectations, the major contribution to strand breaks is from resonances at around 7 eV while resonances at very low energy (<2 eV) have little influence on strand breaks.
卤代碱基被用作癌症放射治疗中的放射增敏剂，增强 DNA 对次级低能电子 (LEE) 的反应性。LEE 通过离解电子俘获 (DEA) 在特定能量 (共振) 处诱导 DNA 链断裂。尽管卤代碱基在气相中各种电子能量下表现出强烈的 DEA 共振，但在 DEA 可能发生的广泛电子能量范围内 (<12 eV) ，研究卤代碱基对实际 DNA 链断裂的影响本质上是困难的。通过使用 DNA 折纸纳米结构，我们确定了用 8-溴腺嘌呤 (A) 修饰的寡核苷酸的链断裂截面的能量依赖性。这些结果与气相中分离的 A 的 DEA 测量值进行了评估。与预期相反，主要的链断裂来自大约 7 eV 的共振，而非常低的能量 (<2 eV) 的共振对链断裂几乎没有影响。
