DNA光复活过程电子转移机理的脉冲辐解研究

Pulse Radiolysis Studies of the Electron Transfer Mechanism in the DNA Photoreactivation Process

采用脉冲辐解瞬态吸收光谱法研究了水溶液中水合电子引发cis-syn型1,3-二甲基尿嘧啶环丁烷型二聚体(DMUD)裂解,生成嘧啶单体和嘧啶阴离子自由基,以及在维生素K3存在下,嘧啶阴离子自由基和VK3之间的电子转移反应过程,测定了电子转移反应的速率常数.当没有VK3作为电子受体时,嘧啶阴离子自由基能继续和DMUD进行链反应.

Utilizing a pulse radiolysis equipment with time-resolved optical detector, kinetic processes of electron-induced splitting of cis-syn 1, 3-dimethyluracil cyclabutane dimer （DMUD） in aqueous solution are investigated in the presence or absence of Vitamin K3 （VK3）. It has been observed that cyclobutane pyrimidine dimer reacting with hydrated electron splits spontaneously to give a monomer and a monomer radical species and the rate constants of election transfer from the monomer radical anion to VK3 have been determined. On the basis of comparison of the interactions between DMUD and hydrated electron in the presence and absence of VK3, a chain reaction process in the absence of VK3 has been demonstrated.