DNA MEDIATED ELECTRON TRANSFER REACTIONS

DNA 介导的电子转移反应

• 批准号: 2838604
• 负责人: JACQUELINE K BARTON
• 金额: $ 31.57万
• 依托单位: CALIFORNIA INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-03-01 至 2003-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2838604
• 关键词: DNA; DNA damage; DNA repair; azapurine; electron transport; guanine analog; high performance liquid chromatography; imines; metal complex; molecular stacking; mutagens; nucleic acid structure; nucleoside analog; osmium; phenanthrene; phenazines; quinones; rhodium; ruthenium

The overall objective of the proposed research is to delineate how the DNA base pair stack may mediate long range charge transport. The consequences of long range radical migration through DNA are important to consider with respect to understanding carcinogenesis and to developing new chemotherapeutic strategies. Long range electron transfer chemistry in DNA will be probed using well-defined duplex assemblies with well stacked donors and acceptors. Studies in the current grant period with intercalators as probes have shown that DNA- mediated electron transfer can proceed with a shallow dependence on distance but a high sensitivity to base pair stacking. Assemblies will be constructed in which the donor/acceptor pair are (i) both intercalators, (ii) one intercalator, one modified base, or (iii) two modified bases. The tethered intercalators include phenanthrene quinone diimine of rhodium, dipyridophenazine complexes of ruthenium and osmium, and ethidium. The modified bases include 2-aminopurine, deazaguanine, and oxoguanine. Fluorescence and transient absorption experiments will be conducted to determine rates of electron transfer as a function of distance, sequence, and driving force. Ru(II)/Os(II) modified assemblies will be prepared to examine triplet energy transfer, and Ru(II)/Os(III) assemblies will be used to test for intervalence charge transfer. DNA assemblies containing a tethered Ru(III) intercalator and a tethered Lys-Trp-Lys will be constructed as a model to explore protein-DNA electron transfer. By considering double helical DNA not only as a bridge but also as a reactant, in the past grant period, we exploited the DNA base pair stack to carry out chemistry at a distance, where oxidation is promoted from a remote site to damage or repair DNA. Thus we propose to couple spectroscopic and biochemical assays using defined DNA assemblies to examine how oxidative damage to DNA occurs at a distance. Oxidative DNA damage initiated from a remote site using an intercalating oxidant will be characterized through variations in intervening DNA sequence, structure, and conformation. The effects of protein-induced changes in the base pair stack, notably base flipping, on long range oxidative damage will also be examined in an effort to develop solution assays for protein-promoted helix distortions. Additionally, oxidative damage to DNA will be compared on DNA fragments and within nucleosomes to determine how DNA packaging affects long range charge transport. Our long term objective is to establish whether charge transport through DNA is physiologically important in the long range transmission of chemical information.

拟议研究的总体目标是描述 DNA碱基对堆叠可以介导长距离电荷传输。 的 通过DNA的长距离自由基迁移的结果是重要的 来理解致癌作用， 开发新的化疗策略。 长程电子 将使用定义明确的双链体探测DNA中的转移化学 具有良好堆叠的施主和受主的组装体。 的研究 目前的赠款期与嵌入剂作为探针表明，DNA- 介导的电子转移可以进行， 距离，但对碱基对堆叠的高灵敏度。 组件将 其中供体/受体对是（i）两者 嵌入剂，（ii）一种嵌入剂，一种修饰的碱基，或（iii）两种 修改基地栓系插层剂包括菲醌 铑的二亚胺，钌和锇的二吡啶并吩嗪络合物， 和乙锭。 修饰的碱基包括2-氨基嘌呤，脱氮鸟嘌呤， 和氧代鸟嘌呤。 荧光和瞬态吸收实验将 进行，以确定作为函数的电子转移速率， 距离、顺序和驱动力。 Ru（II）/Os（II）修饰 将准备组装以检查三重态能量转移， Ru（II）/Os（III）组装体将用于测试价间电荷 转移含有拴系的Ru（III）嵌入剂的DNA组装体， 将构建一个拴系的Lys-Trp-Lys作为模型来探索 蛋白质-DNA电子转移 通过考虑双螺旋DNA， 既作为桥梁，又作为反应物，在过去的赠款期间， 利用DNA碱基对堆栈在远处进行化学反应， 其中氧化从远端位点促进以损伤或修复DNA。 因此，我们建议将光谱和生物化学测定结合起来， 定义的DNA组装，以研究如何氧化损伤的DNA发生在 远处氧化性DNA损伤从一个遥远的网站启动，使用 嵌入氧化剂的特征在于 插入DNA序列、结构和构象。 的影响 蛋白质诱导的碱基对堆积的变化，特别是碱基翻转， 对长距离氧化损伤也将进行检查， 开发蛋白质促进的螺旋扭曲的溶液测定法。 此外，将在DNA片段上比较对DNA的氧化损伤 以及核小体内的DNA，以确定DNA包装如何影响长距离 电荷传输我们的长期目标是确定是否收取 通过DNA的运输在长距离上是生理上重要的 化学信息的传递。