RADIATION-INDUCED SULFHYDRYL AUTOXIDATION AND THE OER

这个项目的主要目标是阐明硫醇对 DNA在缺氧条件下辐照后发生的自由基过程 以及有毒的环境。这些研究将测试这种化学物质的三种模型 氧增强作用，并将探讨自由基机制 硫醇辐射防护。这些研究将使用电子自旋共振 光谱学、高效液相色谱和气相色谱-质谱法，并在 强调辐射直接影响的条件。通过 冷冻缺氧和充氧DNA-硫醇溶液的辐照 电子自旋共振谱的仔细分析 DNA的阴离子、阳离子和中性转移机制 不同电荷的硫醇的自由基位置将被阐明。高效液相色谱仪和 将使用GC-MS来鉴定样品中的DNA和硫醇产物 经ESR分析。产品分析将检验阐明的机理。 由ESR提供。根据这一分析，O2在与DNA自由基反应中的作用 并与硫醇一起测定自由基。主要的DNA自由基 最容易与硫醇反应，以及硫醇自由基的身份 在这些反应中产生的中间产物将被测定。的反应 将搜索带有DNA的亚砜自由基。二硫化物的作用 阴离子自由基在化学增氧中的作用将被阐明 通过对一系列二硫化物的调查。个体DNA碱离子 自由基将在核苷酸及其与硫醇的反应上形成 为了阐明自由基转移的效率而进行的研究 各个基地中的每一个。在这些模型系统工作的后期阶段 多核苷酸和寡核苷酸也将被调查。角色 组蛋白的自由基转移到带电硫醇的过程将是 也进行了调查。精胺等多胺也将被用作 竞争性结合剂。更改相对浓度的 硫醇/结合物种将进一步深入了解 硫醇结合到自由基转移，并作为模型的影响 组蛋白-DNA相互作用对自由基向硫醇转移的影响。

The primary goal of this project is to elucidate the effect of thiols on the free radical processes that occur in DNA after irradiation under anoxic and oxic conditions. These studies will test three models for the chemical oxygen enhancement effect and will investigate free radical mechanisms for thiol radioprotection. The studies will employ electron spin resonance spectroscopy and HPLC and GC-mass spectroscopy and are performed under conditions that emphasize the direct effect of radiation. Through the irradiation of frozen anoxic and oxygenated DNA-thiol solutions and the careful analysis of electron spin resonance spectra the free radical mechanisms involved in the transfer of DNA anionic, cationic and neutral radical sites to thiols of differing charge will be elucidated. HPLC and GC-MS will be employed to identify DNA and thiol products in the samples analyzed by ESR. The product analyses will test the mechanisms elucidated by ESR. From this analysis the role of O2 in reactions with DNA radicals and with thiol radicals will be determined. The primary DNA radicals which react most readily with thiols, and the identity of the thiol radical intermediates produced in these reaction will be determined. Reactions of sulfoxyl radicals with DNA will be searched for. The role of the disulfide anion radical in the chemical oxygen enhancement effect will be elucidated by an investigation of a series of disulfides. Individual DNA base ion radicals will be formed on nucleotides and their reaction with thiols investigated in order to elucidate the efficiency of radical transfer from each of the various bases. At a later stage of work on these model systems polynucleotides and oligonucleotides will also be investigated. The role of histones on the radical transfer process to charged thiols will be investigated as well. Polyamines such as spermine will also be employed as competitive binding agents. Changing the relative concentration of thiol/binding species will provide further insight into the importance of thiol binding to radical transfer and act as a model for the effect of histone-DNA interactions on radical transfer to thiols.