通过DNA四向连接体的电荷传输。
Charge transport through DNA four-way junctions.
作者信息
Odom D T, Dill E A, Barton J K
机构信息
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
出版信息
Nucleic Acids Res. 2001 May 15;29(10):2026-33. doi: 10.1093/nar/29.10.2026.
Long range oxidative damage as a result of charge transport is shown to occur through single crossover junctions assembled from four semi-complementary strands of DNA. When a rhodium complex is tethered to one of the arms of the four-way junction assembly, thereby restricting its intercalation into the pi-stack, photo-induced oxidative damage occurs to varying degrees at all guanine doublets in the assembly, though direct strand scission only occurs at the predicted site of intercalation. In studies where the Mg(2+) concentration was varied, so as to perturb base stacking at the junction, charge transport was found to be enhanced but not to be strongly localized to the arms that preferentially stack on each other. These data suggest that the conformations of four-way junctions can be relatively mobile. Certainly, in four-way junctions charge transport is less discriminate than in the more rigidly stacked DNA double crossover assemblies.
电荷传输导致的远距离氧化损伤被证明是通过由四条半互补DNA链组装而成的单交叉连接发生的。当铑配合物连接到四向连接组装体的一个臂上，从而限制其插入π堆积时，光诱导的氧化损伤在组装体中的所有鸟嘌呤双峰处都有不同程度的发生，尽管直接链断裂只发生在预测的插入位点。在镁离子浓度变化以扰乱连接点处碱基堆积的研究中，发现电荷传输增强，但并未强烈局限于优先相互堆积的臂上。这些数据表明四向连接的构象可能相对灵活。当然，在四向连接中，电荷传输比在堆积更紧密的DNA双交叉组装体中更不具选择性。
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