N_2O饱和胞嘧啶水溶液体系辐解的瞬态产物研究

Study on Transient Products Induced by Pulse Radiolysis of Cytosine Aqueous Solution Saturated with N_2O

在确定胞嘧啶阴离子自由基（Ｃｙｔ．）特征吸收的基础上，采用脉冲辐解技术，以Ｎ２Ｏ作为ｅ－ａｑ的清除剂对Ｃｙｔ水溶液进行了研究。实验结果显示：在不存在自由ｅ－ａｑ条件下仍产生了Ｃｙｔ的两个特征吸收峰，即位于λｍａｘ＝３５５±５ｎｍ处的Ｃｙｔ．吸收峰和其质子化产物的吸收峰。Ｃｙｔ．按一级动力学方式衰减，但在同一ｐＨ值下较Ｎ２饱和溶液体系的慢。从而推测，Ｎ２Ｏ－可与Ｃｙｔ形成电子转移授受络合物，这种络合物的形成导致Ｃｙｔ．的λｍａｘ兰移，同时由于Ｎ２Ｏ－与Ｈ２Ｏ反应使溶液ｐＨ值上升而使Ｃｙｔ．

On the basis of detemining the characteristic absorption of cytosine anion radical (Cyt.),we studied the Cyt aqueous solution using the pulse radiolysis and e - aq savenger N_2O.Results showed that the two characteristic absorptions of Cyt were also produced,that was characteristic absorption of Cyt. located at λ=335±5nm and the characteristic absorption for protonated products of Cyt..Cyt. decayed follwing the first order kinetics,but slower than it did at the same pH value solution saturated with N_2.We suspected that N_2O~ - can produce the EDA complex of electron transfer with Cyt,this EDA complex leads to the blue movement of the characteristic absorption,and that the pH rised with the reaction of N_2O~ - and H_2O leads to the increase the τ/2 of Cyt..