How Does the O-6-Methylation Regulate the Excited-State Decay of Guanine Monomers
How Does the O-6-Methylation Regulate the Excited-State Decay of Guanine Monomers
复制标题
O-6-甲基化如何调节鸟嘌呤单体的激发态衰变
DOI：
10.1021/acs.jpcb.8b08606
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发表时间：
2019
影响因子：
3.3
通讯作者：
Zhao Li
中科院分区：
文献类型：
--
作者：
Zhou Panwang;Zhao Li
本文采用多重参考方法和隐式溶剂化模型，以9-甲基-O_6-甲基鸟嘌呤（9 Me-6 MeGua）为模型化合物，研究了O_6-甲基鸟嘌呤在水溶液中的光诱导超快失活过程。虽然四个S1/S 0最小能量圆锥交点（MECIs）的位置，能量分布表明，只有其中两个参与激发态衰变过程，并占C2和C6反应坐标，分别。为了达到这两个相关的MECI，9 Me-6 MeGua需要克服一个能量障碍。计算的C6反应坐标的能垒是非常低的，应该负责实验观察到的快速内转换（IC）过程（10.95 ps），而C2反应坐标占慢IC过程（10.41 ps）。最后，我们给出了6 MeGuo超快失活的详细机制，这很好地解释了最近的实验结果[Ashwood，B; J. Phys. Chem. Lett.2017，8，4380 - 4385]并修改了提出的机制。
In this study, the photoinduced ultrafast deactivations ofO6-methylguanosine in aqueous solution are mapped by employing multireference methods with implicit solvation model on a reduced model compound 9-methyl-O6-methylguanine (9Me-6MeGua). Although four S1/S0minimal energy conical intersections (MECIs) are located, energy profiles indicated that only two of them are involved in excited-state decay processes and account for the C2 and C6 reaction coordinates, respectively. To reach both the involved MECIs, 9Me-6MeGua needs to surmount an energy barrier. The computed energy barrier of the C6 reaction coordinate is extremely low and should be responsible for the experimentally observed fast internal conversion (IC) process (∼0.95 ps), whereas the C2 reaction coordinate accounts for the slow IC process (∼41 ps). Eventually, we deliver a detailed mechanism for ultrafast deactivations of 6MeGuo, which explains well the recent experimental results [Ashwood, B.;J. Phys. Chem. Lett.2017, 8, 4380−4385] and revises the proposed mechanism.