更生霉素-DNA反应的电化学研究

Electrochemical Studies of Reaction Between Dactinomycin and DNA

研究了更生霉素 (Act-D)在活化浸蜡石墨电极上的电化学特性 ,发现在 -0 .1 9和 -0 .5 1 V分别出现一个灵敏的氧化峰和还原峰 ,加入 DNA使 Act-D的峰电流明显降低 ,生成了非电活性络合物 .采用电化学方法研究了 Act-D与小牛胸腺 DNA的结合平衡 ,根据不可逆电活性分子与 DNA相互作用的电化学公式对实验数据进行非线性拟合 ,获得了 Act-D的扩散系数、Act-D与 DNA的结合常数和结合位点数等重要信息 ,发现 Act-D与 DNA的 8个碱基对紧密结合 ,其侧链加强了结合程度 .

The electrochemical behavior of Dactinomycin(Act-D) and the interaction between Act-D and DNA were investigated by using electrochemical method. In 0.1 mol/L NaH 2PO 4-Na 2HPO 4 buffer(pH=7.0), Act-D showed a pair of oxidative and reductive peaks at -0.19 and -0.51 V in the cyclic voltammetry. Act-D reacted with DNA and formed an non-electroactive complex, resulting in a decrease of reductive current. The diffusion coefficient of Act-D(D), binding constant(K) and binding site size(s) of Act-D and DNA were obtained simultaneously by nonlinear fitting analysis of electrochemical data based on an electrochemical equation for examining the interaction between irreversible redox compounds and DNA. The results were: D f=2.0×10 -5 cm 2·s -1, K=5.87×10 9 cm 3·mol -1, s=8.3. The overall results demonstrate that Act-D binds tightly to eight base pairs of ctDNA. The two cyclic penta-depsipeptides of Act-D reinforce the interaction with DNA.