Electron spin resonance of DNA irradiated with a heavy-ion beam (O-16(8+)): Evidence for damage to the deoxyribose phosphate backbone
Electron spin resonance of DNA irradiated with a heavy-ion beam (O-16(8+)): Evidence for damage to the deoxyribose phosphate backbone
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DOI：
10.2307/3579297
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发表时间：
1996-10-01
影响因子：
3.4
通讯作者：
Sevilla, MD
中科院分区：
文献类型：
--
作者：
Becker, D;Razskazovskii, Y;Sevilla, MD
用ESR谱研究了重离子束辐照水合DNA产生的自由基。低温（77 K）下60 MeV/核子O-16（8+）离子束辐照后形成的主要自由基种类与以前用低LET辐射、嘧啶电子增益自由基和嘌呤电子损失自由基研究中确定的相同;然而，在较高的LET辐射下，发现中性碳中心自由基的相对量更大，并鉴定出一个新的磷中心自由基。中性碳自由基的分数也被发现增加沿着离子束轨道与布拉格峰中发现的最高金额。中性碳中心自由基可能部分来自糖部分。在77 K时，O-16（8+）离子束的G值明显小于低LET辐射的G值。新的磷为中心的自由基物种被确定其大的P-31平行超精细耦合约780 G的磷酰基自由基。这种物质的产生与剂量呈线性关系，在低LET辐射照射的DNA中没有发现大量的这种物质。磷酰基自由基必须由P-O键断裂产生，并表明直接链断裂的可能性。磷酰基物种的产量是小的（约0.1%的所有自由基），然而，它清楚地表明，新的损伤机制，这是不显着的低LET辐射必须考虑高LET辐射。(C)1996年，辐射研究学会
The free radicals produced from the irradiation of hydrated DNA with a heavy-ion beam have been investigated by ESR spectroscopy. The dominant free radical species formed after 60 MeV/nucleon O-16(8+) ion-beam irradiations at low temperatures (77 K) are the same as those previously identified from studies using low-LET radiation, pyrimidine electron-gain radicals and purine electron-loss radicals; however, greater relative amounts of neutral carbon-centered radicals are found with the higher-LET radiation, and a new phosphorus-centered radical is identified. The fraction of neutral carbon radicals is also found to increase along the ion-beam track with the highest amounts found in the Bragg peak. The neutral carbon-centered radicals likely arise in part from the sugar moiety. The G values found for total trapped radicals at 77 K are significantly smaller for the O-16(8+) ion beam than those found for low-LET radiation. The new phosphorus-centered radical species is identified by its large P-31 parallel hyperfine coupling of about 780 G as a phosphoryl radical. This species is produced linearly with dose and is not found in significant amounts in DNA irradiated with low-LET radiation. The phosphoryl radical must be produced by the fragmentation of a P-O bond and suggests the possibility of a direct strand break. The yield of phosphoryl species is small (about 0.1% of all radicals); however, it clearly indicates that new mechanisms of damage which are not significant for low-LET radiation must be considered for high-LET radiation. (C) 1996 by Radiation Research Society