Oxidation of DNA-bound peptides and proteins by DNA-mediated electron transfer reactions

DNA电荷传输化学已经成为相当感兴趣的主题，在诱变和分子电子学等不同领域可能产生影响。该项目的目标是将DNA介导的电荷转移过程置于生物学背景下。在这个项目中，采用了两种不同的方法来研究肽和蛋白质如何影响或调节通过DNA的电荷转移过程。在第一部分中，将小的DNA结合肽连接到寡核苷酸的5 '-末端。电荷转移过程的光引发的嵌入钌光氧化剂使用闪光猝灭技术。在第二部分中，电荷传输和自由基捕获的DNA组件中的存在下，位点特异性结合的DNA相互作用的酶，如胞嘧啶甲基转移酶“HHal”突变体和烷基腺嘌呤糖基化酶检查。通过DNA碱基堆叠的电荷迁移已被探测到光谱观察自由基中间体的形成和生化评估不可逆的氧化DNA损伤。鸟嘌呤自由基在50 A以上时观察到蛋白质依赖的DNA电荷传输。鉴于时间尺度和距离制度，这种蛋白质依赖的DNA电荷传输化学需要考虑生理。

DNA charge transport chemistry has been the subject of considerable interest with possible consequences in areas as diverse as mutagenesis and molecular electronics. The goal of this project was to put DNA-mediated charge transfer processes in a biological context. In this project, two different approaches were made to investigate how peptides and proteins influence or modulate charge transfer processes through the DNA. In the first part, small DNA-binding peptides were tethered convalently to the 5`-terminus of oligonucleotides. Charge transfer processes were photoinitiated by an intercalating ruthenium photooxidant using the flash-quench technique. In the second part, charge transport and radical trapping were examined in DNA assemblies in the presence of site-specifically bound DNA-interacting enzymes such as cytosin methyltransferase "Hhal" mutants and alkyladenine glycosylase. Charge migration through the DNA base stack has been probed both spectroscopically to observe the formation of radical intermediates and biochemically to assess irreversible oxidative DNA damage. Protein-dependent DNA charge transport is observed over 50 A with guanine radicals. Given the time scale and distance regime such protein-dependent DNA charge transport chemistry requires consideration physiologically.