DNA Charge Transport Chemistry and Biology

描述（由申请人提供）：本申请的长期目标是了解DNA介导的电荷传输（CT）化学和生物学以及氧化性DNA损伤和修复的影响。我们实验室的研究表明，DNA CT可以在长的分子距离上进行，以序列和结构依赖的方式影响损伤，并且可以通过DNA结合蛋白进行调节。反应对堆积非常敏感。现在有人建议，以描绘DNA CT的生物后果和机会。将使用嵌入光氧化剂探索细胞核内DNA的氧化损伤。DNA损伤将在染色体的端粒区域和邻接外显子的CpG岛内进行探测，以测试这些区域是否提供损伤通过DNA CT汇集的汇。将比较转录活性区与非活性区。CT损伤的距离范围将通过三重靶向在体内建立。DNA结合蛋白是否有利地利用DNA CT也将被检查。碱基切除修复酶家族，特别是MutY和Endo III，将被探测到它们的DNA结合的氧化还原化学。瞬时吸收，EPR，电化学，DNA修饰电极和生物化学方法将用于表征蛋白质/DNA CT使用野生型和突变蛋白。自旋陷阱探测DNA介导的CT涉及DNA结合蛋白将被开发。还将检查转录激活因子SoxR以测试DNA介导的CT是否用于长距离信号传导和激活。将使用电化学和瞬态吸收光谱法检查DNA介导反应中DNA结合的转录因子在远距离的氧化，并将用生物化学方法探测SoxR的远距离活化。同时，瞬态吸收，荧光和生物化学方法将被用于定义明确的寡核苷酸组件，以探测DNA CT相关的生物背景的重要特征。修饰的碱基和鸟嘌呤将作为氧化的目标。电子与空穴传输将被检查和比较。其他化学陷阱还原和氧化的CT除了鸟嘌呤损伤将被征召，包括胸腺嘧啶二聚体修复。

DESCRIPTION (provided by applicant): The long term objective of this proposed application is an understanding of DNA-mediated charge transport (CT) chemistry and biology and implications with respect to oxidative DNA damage and repair. Studies in our laboratory have shown that DNA CT can proceed over long molecular distances to effect damage, in a sequence- and structure-dependent fashion, and can be modulated by DNA-binding proteins. The reaction is exquisitely sensitive to stacking. It is proposed now to delineate the biological consequences and opportunities for DNA CT. Oxidative damage to DNA within the cell nucleus will be explored using intercalating photooxidants. DNA damage will be probed in telomeric regions of the chromosome and within CpG islands bordering exons to test whether these regions provide sinks to which damage is funneled by DNA CT. Transcriptionally active versus inactive regions will be compared. The distance range for CT damage will be established in vivo by triplex targeting. Whether DNA-binding proteins utilize DNA CT advantageously will also be examined. The family of base excision repair enzymes, notably MutY and Endo III, will be probed as to their DNA-bound redox chemistry. Transient absorption, EPR, electrochemistry, on DNA-modified electrodes and biochemical methods will be utilized to characterize protein/DNA CT using wild type and mutant proteins. Spin traps to probe DNA-mediated CT involving the DNA-bound protein will be developed. Also the transcriptional activator, SoxR will be examined to test whether DNA-mediated CT is exploited for long range signaling and activation. Oxidation of the DNA-bound transcription factor at long range in a DNA-mediated reaction will be examined using electrochemistry and transient absorption spectroscopy and the long range activation of SoxR will be probed biochemically. In parallel, transient absorption, fluorescence and biochemical methods will be utilized in well-defined oligonucleotide assemblies to probe the important characteristics of DNA CT relevant to the biological context. Modified bases and guanines will serve as targets of oxidation. Electron versus hole transport will be examined and compared. Other chemical traps for reductive and oxidative CT besides guanine damage will be enlisted including thymine dimer repair.