Modelling and calculations are presented as a first step towards mechanistic interpretation and prediction of radiation effects based on the spectrum of initial DNA damage produced by low energy electrons (100 eV-4.5 keV) that can be compared with experimental information. Relative yields of single and clustered strand breaks are presented in terms of complexity and source of damage, either by direct energy deposition or by reaction of OH radicals, and dependence on the activation probability of OH radicals and the amount of energy required to give a single strand break (ssb). Data show that the majority of interactions in DNA do not lead to damage in the form of strand breaks and when they do occur, they are most frequently simple ssb. However, for double-strand breaks (dsb), a high proportion (approximately 30%) are of more complex forms, even without considering additional complexity from base damage. The greater contribution is from direct interactions in the DNA but reactions of OH radicals add substantially to this, both in terms of the total number of breaks and in increasing the complexity within a cluster. It has been shown that the lengths of damaged segments of DNA from individual electron tracks tend to be short, indicating that consequent deletion length (simply by loss of a fragment between nearby dsb) would be short, very seldom exceeding a few tens of base pairs.

译文

建模和计算是基于低能电子 (100 eV-4.5 keV) 产生的初始DNA损伤谱的辐射效应的机械解释和预测的第一步,可以与实验信息进行比较。通过直接能量沉积或OH自由基的反应,以及对OH自由基的激活概率和产生所需能量的依赖,以复杂性和损伤来源表示单链断裂 (ssb)。数据表明,DNA中的大多数相互作用不会以链断裂的形式导致损伤,当它们发生时,它们最常见的是简单的ssb。然而,对于双链断裂 (dsb),高比例 (约30%) 是更复杂的形式,甚至不考虑来自基础损伤的额外复杂性。更大的贡献来自DNA中的直接相互作用,但是OH自由基的反应在断裂总数和增加簇内的复杂性方面都大大增加了这一点。已经表明,来自单个电子轨道的DNA受损片段的长度往往很短,这表明随之而来的缺失长度 (仅通过附近dsb之间的片段丢失) 将很短,很少超过几十个碱基对。

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