Marín D, Pérez P, Teijeiro C, Palecek E
Departamento de Química Fisica, Universidad de Alcalá, Madrid, Spain.
Biophys Chem. 1998 Nov 16;75(2):87-95. doi: 10.1016/s0301-4622(98)00190-2.
The anti-cancer drug mitomycin C (MC) was acid-activated and its interaction with single-stranded calf thymus DNA, immobilized at the surface of the hanging mercury drop electrode (DNA-modified HMDE) was studied by cyclic voltammetry. It was found that immersion of the DNA-modified electrode in a solution of acid-activated MC (at pH 3.9) for a short time (usually 1 min) at open current circuit, followed by transfer of the electrode in a neutral blank background electrolyte, resulted in a decrease of the anodic peak G (due to guanine residues in DNA) and in the formation of a reversible couple at approx. -0.44 V. The potential of the cathodic peak was approx. 50 mV more negative than the cathodic peak of the acid-activated MC obtained under the same conditions in the absence of DNA. No changes of peak G occurred and only a very small cathodic peak appeared if the DNA-modified electrode was immersed in an MC solution not exposed to acid pH. On the basis of these results and additional experiments, including dependence on concentration, time and pH during the interaction of MC with DNA at the electrode surface, we concluded that acid-activated MC is covalently bound to guanine residues in DNA immobilized at the electrode surface and that the quinone group in the DNA-MC adduct is reversibly reduced at the electrode.
抗癌药物丝裂霉素C（MC）经酸活化后，通过循环伏安法研究了其与固定在悬汞滴电极表面的单链小牛胸腺DNA（DNA修饰的HMDE）的相互作用。研究发现，将DNA修饰电极在开路电流下于酸活化的MC溶液（pH 3.9）中短时间（通常1分钟）浸泡，然后将电极转移至中性空白背景电解质中，会导致阳极峰G（归因于DNA中的鸟嘌呤残基）降低，并在约-0.44 V处形成一个可逆偶合。阴极峰的电位比在相同条件下无DNA时获得的酸活化MC的阴极峰负约50 mV。如果将DNA修饰电极浸入未暴露于酸性pH的MC溶液中，则峰G无变化，仅出现一个非常小的阴极峰。基于这些结果以及包括MC与电极表面DNA相互作用期间对浓度、时间和pH的依赖性等额外实验，我们得出结论：酸活化的MC与固定在电极表面的DNA中的鸟嘌呤残基共价结合，并且DNA-MC加合物中的醌基团在电极上可逆还原。
