堆积
电子转移
DNA
碱基对
猝灭(荧光)
背景(考古学)
碱基
光诱导电子转移
化学
电子受体
电子传输链
光化学
生物物理学
荧光
生物
生物化学
物理
有机化学
古生物学
量子力学
作者
Shana O. Kelley,Jacqueline K. Barton
出处
期刊:Chemistry & Biology
[Elsevier]
日期:1998-08-01
卷期号:5 (8): 413-425
被引量:135
标识
DOI:10.1016/s1074-5521(98)90158-2
摘要
The DNA double helix is composed of an array of aromatic heterocyclic base pairs and, as a molecular pi-stack, represents a novel system for studying long-range electron transfer. Because many base damage and repair processes result from electron-transfer reactions, the ability of DNA to mediate charge transport holds important biological implications. Seemingly contradictory conclusions have been drawn about electron transfer in DNA from the many different studies that have been carried out. These studies must be reconciled so that this phenomenon can be understood both at a fundamental level and in the context of biological systems.The photoinduced oxidation of a modified base, 7-deazaguanine, has been examined as a function of distance, sequence, and base stacking in DNA duplexes covalently modified with ethidium. Over ethidium/deazaguanine separations of 6-27 A, the photooxidation reaction proceeded on a subnanosecond time scale, and the quenching yield exhibited a shallow distance dependence. The efficiency of the reaction was highly sensitive to small changes in base composition. Moreover, the overall distance-dependence of the reaction is sensitive to sequence, despite the constancy of photoexcited ethidium as acceptor.The remarkable efficiency of deazaguanine photooxidation by intercalated ethidium over long distances provides new evidence for fast electron-transfer pathways through DNA. By varying sequence as well as reactant separation, this work provides the first experimental demonstration of the importance of reactant stacking in the modulation of long-range DNA mediated electron transfer.
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