Sequence dependence of charge transport through DNA domains
Sequence dependence of charge transport through DNA domains
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DOI：
10.1021/ja0563399
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发表时间：
2005-12-14
影响因子：
15
通讯作者：
Barton, JK
中科院分区：
文献类型：
--
作者：
Shao, FW;Augustyn, K;Barton, JK
在这里，我们研究了两个动力学快速电子空穴陷阱，N-4-环丙基胞嘧啶（C-CP）和N-2-环丙胺-鸟苷（（CP）G），纳入不同序列的DNA双链体使用不同的光氧化剂的光氧化。用非共价键合的[Ru（phen）（dppz）（bpy '）]（3+）（dppz = dipridophenazine）和[Rh（phi）（2）（bpy）]（3+）（phi =菲醌二亚胺）或用拴在DNA上的蒽醌进行DNA氧化研究。由于环丙胺取代的碱在氧化时迅速分解，它们的分解效率提供了相对空穴定位的量度。与DNA中C-CP相对于（CP）G的更高氧化电位一致，C-CP通过[Rh（phi）（2）（bpy）]（3+）的光氧化而分解，而（CP）G通过光激发的[Rh（phi）（2）（bpy）]（3+）和[Ru（phen）（dppz）（bpy '）]（3+）进行开环。蒽醌修饰的DNA组件相同的碱基组成，但不同的碱基序列也探测。腺嘌呤束内的单碱基和双碱基取代调节C-CP分解。事实上，可以看到DNA组装体中的整个序列控制C-CP氧化，而不仅仅是介于C-CP和拴系的光氧化剂之间的碱基。这些数据是调和的背景下，构象门控电荷传输通过离域DNA结构域的机械模型。光氧化的蒽醌修饰的DNA组件含有C-CP和（CP）G，但与不同的距离分开的修改后的碱基，点域大小至少为三个碱基。我们的DNA电荷传输模型不同于极化子模型。在我们的模型中，碱基对堆栈内的离域基于序列依赖的DNA结构和动力学瞬时形成。鉴于这些结果，DNA电荷传输确实对DNA序列和结构非常敏感。
Here we examine the photooxidation of two kinetically fast electron hole traps, N-4-cyclopropyl-cytosine (C-CP) and N-2-cyclopropylamine-guanosine ((CP)G), incorporated in DNA duplexes of various sequence using different photooxidants. DNA oxidation studies are carried out either with noncovalently bound [Ru(phen)(dppz)(bpy')](3+) (dppz = dipyridophenazine) and [Rh(phi)(2)(bpy)](3+) (phi = phenanthrenequinone diimine) or with anthraquinone tethered to DNA. Because the cyclopropylamine-substituted bases decompose rapidly upon oxidation, their efficiency of decomposition provides a measure of relative hole localization. Consistent with a higher oxidation potential for C-CP versus (CP)G in DNA, C-CP decomposes with photooxidation by [Rh(phi)(2)(bpy)](3+), while (CP)G undergoes ring-opening both with photoexcited [Rh(phi)(2)(bpy)](3+) and with [Ru(phen)(dppz)(bpy')](3+). Anthraquinone-modified DNA assemblies of identical base composition but different base sequence are also probed. Single and double base substitutions within adenine tracts modulate C-CP decomposition. In fact, the entire sequence within the DNA assembly is seen to govern C-CP oxidation, not simply the bases intervening between C-CP and the tethered photooxidant. These data are reconciled in the context of a mechanistic model of conformationally gated charge transport through delocalized DNA domains. Photooxidations of anthraquinone-modified DNA assemblies containing both C-CP and (CP)G, but with varied distances separating the modified bases, point to a domain size of at least three bases. Our model for DNA charge transport is distinguished from polaron models. In our model, delocalized domains within the base pair stack form transiently based upon sequence-dependent DNA structure and dynamics. Given these results, DNA charge transport is indeed remarkably sensitive to DNA sequence and structure.