Rapid radical formation by DNA charge transport through sequences lacking intervening guanines.
Rapid radical formation by DNA charge transport through sequences lacking intervening guanines.
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DNA 电荷传输通过缺乏插入鸟嘌呤的序列而快速形成自由基。
DOI：
10.1021/ja034326u
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发表时间：
2003
影响因子：
15
通讯作者：
Barton,JacquelineK
中科院分区：
文献类型：
--
作者：
Yoo,Jae;Delaney,Sarah;Stemp,EricDA;Barton,JacquelineK
利用闪光猝灭技术探测含有拴系钌嵌入剂的组装体中的DNA电荷传输，通过激光光谱和生物化学方法研究了甲基吲哚自由基形成的动力学和产率作为DNA序列的函数。在这些组装体中，甲基吲哚部分充当低氧化电位的人工碱。在不含鸟嘌呤碱基插入钌嵌入剂和GMG氧化位点的组装体中，在30 μ m以上的距离处观察到空穴注入和随后的甲基吲哚自由基阳离子的形成，速率≥ 107 s-1。自由基产量，但是，显着敏感的干预碱基错配，没有显着的甲基吲哚自由基形成是明显的干预AA错配。同样关键的是注入部位的顺序;该顺序确定初始空穴定位，从而确定空穴传播的概率。与鸟嘌呤，而不是肌苷附近的网站的空穴注入，减少自由基和远程氧化损伤的产量进行观察。在这种情况下，低能量鸟嘌呤位点的存在用于使空穴局部化，从而减少通过碱基对堆叠的电荷传输。
Using the flash-quench technique to probe DNA charge transport in assemblies containing a tethered ruthenium intercalator, the kinetics and yield of methylindole radical formation as a function of DNA sequence were studied by laser spectroscopy and biochemical methods. In these assemblies, the methylindole moiety serves as an artificial base of low oxidation potential. Hole injection and subsequent formation of the methylindole radical cation were observed at a distance of over 30 Å at rates ≥107s-1in assemblies containing no guanine bases intervening the ruthenium intercalator and GMG oxidation site. Radical yield was, however, strikingly sensitive to an intervening base mismatch; no significant methylindole radical formation was evident with an intervening AA mismatch. Also critical is the sequence at the injection site; this sequence determines initial hole localization and hence the probability of hole propagation. With guanine rather than inosine near the site of hole injection, decreased yields of radicals and long-range oxidative damage are observed. The presence of the low-energy guanine site in this case serves to localize the hole and therefore diminish charge transport through the base pair stack.