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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Electron Hole Transport in DNA
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Electron Hole Transport in DNA

机译：DNA中的电子空穴传输

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摘要

Electron hole transport along DNA chains is studied theoretically. Couplings between the DNA bases adenine, cytosine, guanine, and thymine, placed as in DNA in a single strand or diagonally in a double strand, are calculated using ab initio methods. Coupling as well as reorganization energies, which are also calculated, show a great variation between bases. To decide whether a periodic DNA strand has localized or delocalized electrons, a novel theoretical model that uses reorganization energy and coupling as input, is used. The model suggests that electron holes on infinite one-dimensional chains of periodic DNA localize if the ratio of reorganization energy to coupling is larger than about four. The hole is weakly trapped on an infinite guanine strand (G)_x whereas it is delocalized in thmyine (T)_x and cytosine (C)_x strands. Some mixed DNA strands also show a delocalized behavior, but most are localized to a single G in agreement with EPR measurements. Rates of stepwise hole transfer betweeen G sites in mixed chains are calculated and show agreement with experimental data. In electron-transfer steps between lcoalized sites, the tunneling rate decreases exponentially with distance with a quite large #beta# fator in agreement with earlier theoretical work.
机译：理论上研究了沿DNA链的电子空穴传输。 DNA腺嘌呤，胞嘧啶，鸟嘌呤和胸腺嘧啶的DNA碱基之间的耦合，按从头算的方法计算，以单链形式或以对角线形式放在DNA中。同样计算出的耦合能和重组能显示出碱基之间的巨大差异。为了确定周期性DNA链是否具有局部电子或非局部电子，使用了一种以重组能和耦合为输入的新型理论模型。该模型表明，如果重组能与偶联的比率大于约4，则周期性DNA的无穷一维链上的电子空穴就会定位。该孔被弱地捕获在无限的鸟嘌呤链（G）_x上，而在硫氨酸（T）_x和胞嘧啶（C）_x链上被局域化。一些混合的DNA链也显示出离域的行为，但大多数都与EPR测量一致地被定位为单个G。计算了混合链中G位点之间逐步空穴转移的速率，并与实验数据吻合。在铝化位点之间的电子转移步骤中，隧穿率随着距离的增加而呈指数下降，β值非常大，这与早期的理论工作相符。

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