Fast back electron transfer prevents guanine damage by photoexcited thionine bound to DNA
Fast back electron transfer prevents guanine damage by photoexcited thionine bound to DNA
复制标题
DOI：
10.1021/ja036397z
复制
发表时间：
2003-08-13
影响因子：
15
通讯作者：
Barton, JK
中科院分区：
文献类型：
--
作者：
Dohno, C;Stemp, EDA;Barton, JK
吩噻嗪染料硫氨酸具有高激发态还原电位，在飞秒时间尺度上被鸟嘌呤猝灭。在这里，我们通过凝胶电泳显示，在寡核苷酸双链存在的情况下，用599 nm光照射硫氨酸不会产生永久性的DNA损伤。与鸟嘌呤-5′-单磷酸弱相关的硫氨酸光激发后，通过瞬态吸收光谱检测到还原的质子化硫氨酸自由基和中性鸟嘌呤自由基，表明硫氨酸被鸟嘌呤猝灭是通过电子转移机制发生的。没有永久性鸟嘌呤损伤的自由基形成的观察表明，快速的反向电子转移在控制dna结合分子的损伤产量方面起着关键作用。
The phenothiazinium dye thionine has a high excited state reduction potential and is quenched by guanine on the femtosecond time scale. Here, we show by gel electrophoresis that irradiation of thionine with 599 nm light in the presence of an oligonucleotide duplex does not produce permanent DNA damage. Upon photoexcitation of thionine weakly associated with guanosine-5‘-monophosphate, the reduced protonated thionine radical and neutral guanine radical are detected by transient absorption spectroscopy, indicating that the quenching of thionine by guanine occurs via an electron-transfer mechanism. The observation of radical formation without permanent guanine damage indicates that fast back electron transfer plays a critical role in governing the yield of damage by DNA-binding molecules.