Superexchange Mediated Charge Hopping in DNA
Superexchange Mediated Charge Hopping in DNA
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DOI：
10.1021/jp014232b
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发表时间：
2002-07
影响因子：
2.9
通讯作者：
J. Jortner;M. Bixon;A. A. Voityuk-A.;N. Rösch
中科院分区：
文献类型：
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作者：
J. Jortner;M. Bixon;A. A. Voityuk-A.;N. Rösch
我们探讨了DNA的电子-核能级结构、电子耦合和空穴跳跃输运动力学之间的关系。我们利用电子耦合矩阵元素在DNA中最近邻核碱基之间进行空穴转移（Voityuk，A.一、Jortner，J.; Bixon，M.; Rosch，N.J.Chem.Phys.2001，114，5614）来评估链内和链间超交换电子耦合，其在半经验量子力学-动力学模型的框架内确定空穴跳跃速率。计算“短”G +（T-A）n G（n j 3）双链体中鸟嘌呤（G）之间超交换介导的链内电子偶联jVsuperj 2 Δ exp（-Δ R）的指数距离（R）依赖性，结果为Δ）0.8-0.9 A-1。我们解释了在DNA中存在位点特异性结合的甲基转移酶突变体的情况下时间分辨空穴传输的实验数据（Wagenknecht，H.一、Rajski，S.的R.;帕斯卡尔，M。Stemp，E. D.一、巴顿，J.K. J. Am. Soc.2001，123，4400）在复合顺序、链间和链内超交换介导和直接链间空穴跳跃方面。这种机制解释了速率决定步骤、速率的弱双链体大小依赖性以及通过短（T-A）桥（包含单个介导核碱基）的链间超交换诱导的远程电荷传输。对于长（T-A）n（nJ 3）桥的空穴传输，超交换机制被长（A）n链的热致空穴跳跃（TIH）平行机制所取代.对通过DNA双链体的3 ′-5 ′链上由（T-A）n（n）2-5）桥隔开的7个GG对的空穴传输的实验数据进行动力学分析（Sartor，V.; Boone，E.; Schuster，G. B。J. Phys. Chem. B，2001，105，11057）揭示了超交换-TIH交叉发生在n）nx）3处。对DNA超交换机制适用范围的探索和对超交换机制的突破为深入研究该机制在大尺度化学和生物物理系统中的普遍性和系统特异性奠定了基础。
We explore the relationship between the electronic-nuclear level structure, the electronic couplings, and the dynamics of hole hopping transport in DNA. We utilized the electronic coupling matrix elements for hole transfer between nearest-neighbor nucleobases in DNA (Voityuk, A. A.; Jortner, J.; Bixon, M.; Rosch, N.J. Chem. Phys. 2001, 114, 5614) to evaluate intrastrand and interstrand superexchange electronic couplings, which determine hole hopping rates within the framework of a semiempirical quantum mechanical-kinetic model. Calculations of the exponential distance (R) dependence of the superexchange mediated intrastrand electronic couplings jVsuperj 2 ∝ exp(-‚R) between guanines (G) in "short" G + (T-A)n G( n j 3) duplexes result in ‚ ) 0.8-0.9 A -1 . We interpret the experimental data on time-resolved hole transport in the presence of a site-specifically bound methyl transferase mutant in DNA (Wagenknecht, H.-A.; Rajski, S. R.; Pascally, M.; Stemp, E. D. A.; Barton, J. K. J. Am. Chem. Soc. 2001, 123, 4400) in terms of composite sequential, interstrand and intrastrand superexchange mediated, and direct interstrand hole hopping. This mechanism accounts for the rate determining step, for the weak duplex size dependence of the rate, and for the long- range charge transport induced by interstrand superexchange via short (T-A) bridges, containing a single mediating nucleobase. For hole transfer via longer (T-A)n (n J 3) bridges, the superexchange mechanism is replaced by the parallel mechanism of thermally induced hole hopping (TIH) via long (A)n chains. A kinetic analysis of the experimental data for hole transport through seven GG pairs separated by (T-A)n (n ) 2-5) bridges across the 3'-5' strand of the DNA duplex (Sartor, V.; Boone, E.; Schuster, G. B. J. Phys. Chem. B, 2001, 105, 11057) reveals that the superexchange-TIH crossover occurs at n ) nx ) 3. The explorations of the range of applicability and the breakdown of the superexchange mechanism in DNA lay the foundations for the scrutiny of the universality and system specificity of this mechanism in large-scale chemical and biophysical systems.