直接测量扩展 DNA G- 链段中孔穴跳跃的动力学。一种无偏随机行走。

Direct measurement of the dynamics of hole hopping in extended DNA G-tracts. An unbiased random walk.

机构信息

Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208, USA.

出版信息

J Am Chem Soc. 2010 Oct 20;132(41):14388-90. doi: 10.1021/ja106991f.

DOI:10.1021/ja106991f

PMID:20863110

Abstract

We report the measurement of distance- and temperature-dependent rate constants for charge separation in capped hairpins in which a stilbene hole acceptor and hole donor are separated by A(3)G(n) diblock polypurine sequences consisting of 3 adenines and 1-19 guanines. The longer diblock systems obey the simplest model for an unbiased random walk, providing a direct measurement of k(hop) = 4.3 × 10(9) s(-1) for a single reversible G-to-G hole hopping step, somewhat faster than the value of 1.2 × 10(9) s(-1) calculated for A-tract hole hopping. The temperature dependence for hopping in A(3)G(13) provides values of E(act) = 2.8 kcal/mol and A = 7 × 10(9) s(-1), consistent with a weakly activated, conformationally gated process.

摘要

我们报告了在发夹状分子中测量了距离和温度依赖的电荷分离的速率常数，其中芘醌类空穴受体和空穴供体之间通过由 3 个腺嘌呤和 1-19 个鸟嘌呤组成的 A(3)G(n)嵌段聚嘧啶序列分离。较长的嵌段系统遵循无偏差随机行走的最简单模型，直接测量了单个可逆 G-G 空穴跳跃步骤的 k(hop) = 4.3 × 10(9) s(-1)，略快于计算得到的 A-链段空穴跳跃的 1.2 × 10(9) s(-1)值。A(3)G(13)中的跳跃的温度依赖性提供了 E(act) = 2.8 kcal/mol 和 A = 7 × 10(9) s(-1)的值，与弱激活、构象门控过程一致。