Radiation and hydrogen peroxide induced free radical damage to DNA.
Radiation and hydrogen peroxide induced free radical damage to DNA.
复制标题
DOI：
--
复制
发表时间：
1987-06
期刊：
影响因子：
--
通讯作者：
J. Ward;J. Evans;C. Limoli;P. Calabro-Jones
中科院分区：
文献类型：
--
作者：
J. Ward;J. Evans;C. Limoli;P. Calabro-Jones
在先前的出版物（Ward等人，1985），我们检测了由过氧化氢处理哺乳动物细胞产生的链断裂类型的细胞内DNA损伤的产生。总结一下我们的发现：V79和HeLa细胞在0°C下用过氧化氢处理时不容易被杀死-需要用40 mM处理10分钟才能杀死63%（图1）。然而，这些细胞的DNA在微摩尔水平的试剂下显示出显著水平的单链断裂（SSB）（50微摩尔持续10分钟产生5格雷当量的损伤：每个细胞5，000个SSB（Elkind & Redpath，1977））。这意味着，如果过氧化氢产生的SSB的产率线性依赖于浓度，则每个致死事件每个细胞产生40万个SSB。相比之下，对于电离辐射，每个细胞每个致死事件的SSB产量为1，000（Elkind和Redpath，1977年）。通过使用OH自由基清除剂，我们表明引起损伤的过氧化氢的物质是OH自由基，并且该物质在与DNA反应之前的移动距离平均为15 A。该距离与提出的OH自由基产生及其随后与DNA反应的机制一致：过氧化氢在芬顿反应中与结合到DNA的可变价金属离子反应。随后的研究带来了异常：如果细胞在温度（24°C）或37°C下处理，它们会被较低浓度的过氧化氢杀死（图（DO = 35微摩尔）（霍夫曼）。在过氧化氢浓度高达10 mM时，未发现（每个细胞少于100个）。
In a previous publication (Ward et al., 1985) we examined the production of intracellular DNA damage of the strand break type produced by hydrogen peroxide treatment of mammalian cells. To summarize our findings: V79 and HeLa cells when treated with hydrogen peroxide at 0°C are not readily killed - a treatment with 40mM for 10min is necessary to kill 63% (Figure 1). However the DNA of these cells showed significant levels of single strand breaks (SSB) at micromolar levels of the agent (50micromolar for 10min produced 5 Gray equivalents of damage: 5,000 SSB per cell (Elkind & Redpath, 1977)). This means that, if the yield of SSB produced by hydrogen peroxide is linearly dependent on concentration, 0.4 million SSB are produced per cell per lethal event. In contrast, for ionizing radiation the yield of SSB per cell per lethal event is 1,000 (Elkind & Redpath, 1977). By the use of OH radical scavengers we showed that the species from hydrogen peroxide causing the damage was the OH radical and that the distance travelled by this species prior to reacting with DNA was on average 15 A. This distance is in agreement with the mechanism proposed for the production of OH radicals and their subsequent reaction with DNA:Hydrogen peroxide reacting in a Fenton reaction with a variable valency metal ion bound to the DNA. Subsequent studies brought to anomaly: if the cells were treated at temperature (24°C) or at 37°C, they were killed with lower concentrations of hydrogen peroxide (Figure (DO =35micromolar) (Hofmann We measure the yield of SSB after room temperature treatment. None (less than 100 per cell) were found at concentrations of hydrogen peroxide up to 10mM.