ELECTRONIC COUPLING PROPERTIES OF POLYNUCLEOTIDES

监测快速光诱导电子转移过程的动力学 能够直接研究远程电子相互作用的依赖性 取决于周围介质的介电性质。这项技术 因此，可以用来测量电子耦合和原子核 生物材料的重组能。然而，正确的理解 非共轭分子组分之间的电子相互作用 在很大程度上依赖于设计和构建分子结构的能力 它们是刚性的，其组件间的几何形状定义良好。全 到目前为止，研究的模型系统未能满足这一令人望而生畏的要求。 在这里，我们提出了一种简单的策略，使用多核苷酸，一种基本的 自然界中的建筑单元，用于组装供体-受体(D-A)组件 组织成便于研究电子传输的单元 宿主核苷酸的性质。我们选择把重点放在加倍- 容易容纳的链状合成多核苷酸 嵌入染料分子，最大限度地减少对生物结构的破坏。 这种创新方法允许精确定位两个 预定间隔距离的电子伙伴，范围从 范德华接触超过3纳米，但保持固定的方向。 这第一次提供了探索机制的机会。 涉及非共价键的电子相互作用(通过空间) 耦合，一个难以捉摸的过程，一直没有得到很好的描述。一个 进一步的动机是，这种方法将揭示 DNA中远程电子隧穿的机制，从而提供 对DNA损伤和修复机制的进一步认识 流程。来自这项研究的结果应该有直接的 阐明急流生物内分泌机制的意义 蛋白质或核苷酸起中介作用的反应。

Monitoring the dynamics of rapid photoinduced electron transfer processes enables direct study of the dependence of remote electronic interactions upon the dielectric properties of the surrounding medium. This technique can be used, therefore, to measure electronic coupling and nuclear reorganization energies of biomaterials. However, a proper understanding of electronic interactions between nonconjugated molecular components depends heavily upon the ability to design and build molecular structures that are rigid and whose intercomponent geometry is well defined. All model systems studied to date fail to meet this daunting requisite. Here, we propose a simple strategy that uses polynucleotides, a basic architectural unit in nature, to assemble donor-acceptor (D-A) components into organized units that facilitate study of the electron transporting properties of the host nucleotides. We choose to focus on double- stranded synthetic polynucleotides which readily accommodate intercalating dye molecules with minimum disruption of the biostructure. This innovation approach permits the precise positioning of two electronic partners at predetermined separation distances, ranging from van der Waals contact to over 3 nm, but retaining a fixed orientation. This offers the opportunity, for the first time, to explore mechanisms of electronic interactions involving noncovalent (through space) coupling, an elusive process that has been poorly characterized. A further motivation is that this approach will shed light on the mechanisms of long range electronic tunneling in DNA and thereby provide further understanding of the mechanisms for DNA damage and repair processes. The results originating from this study should have direct relevance for elucidating the mechanisms of rapids biological ET reactions in which proteins or nucleotides function as mediators.