DNA-MEDIATED ELECTRON TRANSFER REACTIONS

DNA 介导的电子转移反应

• 批准号: 2186765
• 负责人: JACQUELINE K BARTON
• 金额: $ 20.74万
• 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 1996-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2186765
• 关键词: chemical transfer reaction; metal complex; molecular stacking; nucleic acid chemical synthesis; nucleic acid structure; oxidation reduction reaction; photoactivation; polymers; ruthenium

The overall objective of this proposal, using metal-nucleic acid chemistry, is to explore the role of DNA as a polymer in mediating electron transfer reactions. Oligonucleotides will be constructed which contain metal complexes covalently linked to the double helix so as to carry out studies of photoinduced electron transfer between the donor- acceptor pairs on a DNA duplex as a function of DNA length, sequence, and structure. The DNA helix, as a synthetically amenable and structurally well characterized polymer, may be useful (i) fundamentally, in delineating aspects of long range electron transfer processes through pi- stacks, (ii) biologically, towards understanding how radical reactions may damage DNA, and (iii) practically, in the development of biosensors. Oligonucleotides will be constructed which contain a metallointercalating donor or acceptor tethered to the 5'-terminus; dipyridophenazine (dppz) complexes of ruthenium(II) will serve as donors and phenanthrenequinone (phi) complexes of rhodium(III) will serve as electron acceptors. Intercalation of the complexes within the helix will be established through luminescence studies of the ruthenium-modified oligonucleotide base-paired with unmodified complement. The position of intercalation and hence the metal-metal distance on the polymer will be established through photocleavage experiments using the rhodium-modified polymer bound to unlabeled complement. Photoelectron transfer rates between the metal sites on a double strand formed by annealing the rhodium-modified polymer to the ruthenium-modified polymer will be determined through time-resolved luminescence and transient absorption spectroscopy. Preliminary results indicate fast photoelectron transfer over 41 angstrome through the DNA duplex. Oligonucleotides which differ in length intervening between the metal donor and acceptor will be prepared to establish the distance-dependence in electron transfer rate, and sequences will be synthesized which can adopt preferentially the A- or Z-conformations to determine the contribution of base stacking to the electron transfer process. To compare through-bond versus a pi-stack mechanism, electron transfer rates will be compared between double helices of the form (5'-Ru- oligonucleotide-Rh-3'). (3'complement-5') and (5'Ru-oligonucleotide- 3').(3'-complement'Rh-5'). Agents which bind site-specifically to the intervening duplex, such as cis-platin, a restriction enzyme, or an alternate, site-specifically bound rhodium complex, will be employed to examine perturbations in the long-range electron transfer process. A potential DNA-"diode" will also be constructed to examine whether the incorporation of electron-donating or accepting groups on the helix can impart a "sequence-dependent" directionality to the electron transfer process.

这项提议的总体目标是使用金属核酸 化学，是探索DNA作为一种聚合物在调节 电子转移反应。寡核苷酸将被构建成 含有共价连接到双螺旋的金属络合物，以便 开展供体之间光诱导电子转移的研究- DNA双链上的受体对作为DNA长度、序列和 结构。DNA螺旋，作为一种可合成的和结构上的 特性良好的聚合物，可能是有用的(I)从根本上说，在 描述了长程电子转移过程的几个方面。 STACKS，(Ii)生物学上，有助于理解自由基反应 可能会损害DNA，以及(Iii)实际上，在生物传感器的发展中。 将构建包含金属嵌入物的寡核苷酸 连接在5‘末端的供体或受体；联吡吩嗪(Dppz) Ru(II)络合物将作为供体和菲醌 Rh(III)的(Phi)络合物将作为电子受体。 将建立螺旋内复合体的插层 Ru修饰的寡核苷酸的发光研究 碱基与未修饰的补语配对。插层位置 因此，聚合物上的金属-金属距离将被确定 通过使用Rh修饰的聚合物进行光切割实验 绑定到未标记的补语。分子间的光电子转移速率 双链上的金属位在双链上的形成 聚合物到Ru修饰的聚合物将通过 时间分辨发光和瞬时吸收光谱。 初步结果表明，光电子转移速度超过41 通过DNA双链进行测序。 插入金属之间的长度不同的寡核苷酸 捐赠者和接受者将准备建立距离依赖关系 在电子转移速率上，将合成出可以 优先采用A构象或Z构象来确定 碱基堆积对电子转移过程的贡献。至 比较通键和pi堆叠机制，电子转移速率 在形式(5‘-Ru-)的双螺旋之间进行比较 寡核苷酸-Rh-3‘)。(3‘-补体-5’)和(5‘-Ru-寡核苷酸- (3‘-补语’Rh-5‘)。结合位点的代理--特别是与 介导性双链，如顺铂、限制性内切酶或 另一种可替代的、结合位点的Rh络合物将被用于 研究远程电子转移过程中的微扰。一个 潜在的DNA“二极管”也将被构建来检查 在螺旋上加入供电子或接受基团可以 使电子转移具有“顺序相关”的方向性 进程。