激发态鸟嘌呤无辐射失活的动力学模拟

Dynamics simulation of deactivation passway for excited state guanine

为了研究DNA碱基在紫外辐射下损伤-修复的机理,采用半经典动力学方法模拟了激发态的鸟嘌呤分子无辐射失活过程.模拟发现了一条新的失活通道,即N7-C8解离,释放的键能转化为分子动能.C8-H的强烈振动会导致无辐射跃迁,使分子在600 fs以内返回基态,从而避免了鸟嘌呤的光损伤.

A semiclassical dynamics simulation study was reported for the non-radiactive deactivation process of guanine molecule,that under excited state induced by UV irradiation,which in order to investigate the mechanism of photodamage and repair of DNA bases.The simualtion finds that dissociation of N7-C8 is a new passway of deactivation.The released bond energy convert to molecular kinetic energy.Strong vibration of C8-H leads to nonadiabatic transition of the molecule to the electronic ground state so that photodamage of guanine is avoided.