The effects of ionizing radiation on DNA: the role of thiols as radioprotectors.
The effects of ionizing radiation on DNA: the role of thiols as radioprotectors.
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电离辐射对 DNA 的影响：硫醇作为辐射防护剂的作用。
DOI：
10.1016/j.lfs.2003.09.068
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Pezeshk,Abbas
中科院分区：
文献类型：
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作者：
Pezeshk,Abbas
N-（2-巯基丙酰基）甘氨酸（PSH）的电子丢失产生了EPR可检测的自由基阴离子PS-SP-。当PSH衍生物在DNA水溶液中冷冻至77 K并暴露于电离辐射时，通过EPR光谱检测到对DNA的正常损伤。然而，在77 K以上退火时，DNA碱基自由基阳离子和阴离子的中心EPR特征给出了归属于PS-SP−σ*-自由基阴离子的中心特征，以及5-6-二氢-5-胸腺基自由基TH的外部特征。有人提出，在冻结，PSH分子被约束到一个玻璃状区域周围的DNA，并且，在退火，电子捐赠给PS自由基，与损失的鸟嘌呤自由基阳离子，G+。PS自由基是无法检测到的，但与另一个PSH分子反应时，给出了PS-SP−自由基阴离子的良好EPR光谱。这些结果表明PSH对其他碱基自由基C−/T−的产率几乎没有影响。此外，TH自由基的增长，形成质子化的胸腺嘧啶自由基阴离子，T-，被检测到。我们的结论是，PSH的主要作用是捕获G+中心，从而可以防止或修复DNA的辐射损伤。
Electron loss from N-(2-mercaptopropionyl) glycine (PSH) gave an EPR detectable radical anion, PS-SP−. When the PSH derivative was frozen in aqueous DNA solutions to 77 K and exposed to ionizing radiation, normal damage to the DNA was detected by EPR spectroscopy. However, on annealing above 77 K, central EPR features for the DNA base radical cations and anions gave central features assigned to PS-SP−σ*-radical anions, together with outer features for 5-6-dihydro-5-thymyl radicals, TH. It is proposed that on freezing, the PSH molecules are constrained into a glassy region around the DNA, and that, on annealing, electron donation gives PS radicals, with loss of quanine radical-cations, G+. The PS radicals were not detectable, but on reaction with another PSH molecule, gave good EPR spectra for PS-SP−radical-anions. These results indicate that PSH had little effect on the yield of the other base radicals C−/T−. Also, growth of TH radicals, formed from protonated thymine radical-anions, T−, were detected. We conclude that the primary effect of PSH is to capture the G+centers, and thus could either prevent or repair radiation damage to DNA.