Adsorptive transfer stripping AC voltammetry of DNA complexes with intercalators

Using alternating current adsorptive transfer stripping voltammetry at hang ing mercury drop electrode (HMDE). conformational changes of DNA due to bin ding of DNA intercalators were studied by means of the measurements of tens ammetric DNA signals of peak 2 and peak 3. Untwisting of DNA by the interca lators in solution resulted in an altered DNA adsorption. After medium exch ange and intercalator removal, the surface-confined DNA probably adopted a restrained structure, with untwisted segments attached to the electrode sur face (yielding peak 2) and superhelical loops extending to the bulk of solu tion. This structure was more resistant to DNA surface denaturation than ds DNA adsorbed at HMDE in the absence of intercalators, which resulted in a d ecreased intensity of DNA peak 3. Similar effects were also observed when D NA was adsorbed at the electrode from a solution of low salt concentration. Upon introduction of DNA single-strand breaks, the specific behavior of DN A-intercalator complexes was eliminated.