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概述了电离辐射诱导体外ＤＮＡ单链断裂（ＳＳＢ）和双链断裂（ＤＳＢ）的形成机理。研究结果 表明， ＤＮＡ链断裂产t额与ＤＮＡ浓度和自由基清除剂的清除力有关，并受ＤＮＡ超螺旋度的影 响； ＤＮＡ α ＤＳＢ除可由直接作用形成外，还可分别由单自由基传递机制和ＬＭＤＳ机制产生；对 高ＬＥＴ辐射， α ＤＳＢ主要由ＬＭＤＳ机制产生。而硫醇类化合物对ＤＮＡ的辐射保护作用则随其 电荷态的增加而增加；由于次级自由基效应，体外ＤＮＡ链断裂具有反向氧效应；非均一动力学 的柱模型被广泛地应用于’ＯＨ等自由基与ＤＮＡ反应的理论研究。
The mechanism of ionizing radiation-induced in vitro DNA single strand break (SSB) and double strand break (DSB) is outlined. The results showed that the DNA strand breaks were related to DNA concentration and the scavenging ability of free radical scavengers and were affected by DNA supercoiling. DNA α DSB could be formed by direct interaction with single free radical Transfer mechanism and LMDS mechanism; for high LET radiation, α DSB is mainly generated by LMDS mechanism. However, the protective effect of thiols on DNA increases with the increase of their charge states. In vitro DNA strand breaks have an inverse oxygen effect due to the secondary free radical effect. Non-uniform kinetic column models are widely used in ’OH and other free radicals and DNA reaction theory research.