THE ELECTROCHEMICAL OXIDATION OF DNA

The electrooxidation mechanism of native and denatured DNA was studied using glassy carbon or tin oxide working electrodes in buffered supporting electrolytes at different pHs. The electrochemical techniques employed were cyclic and differential pulse voltammetry. Significant differences were observed for native and denatured DNA due to the rigidity of the double-stranded structure which impedes the electron transfer from the bases guanine and adenine inside the helix in the former case. For denatured DNA the voltammetric peaks are bigger owing to the adsorption of the single-stranded DNA on the electrode surface. The oxidation of guanine is easier and occurs at lower potentials than the oxidation of adenine. The oxidation of guanosine and adenosine was investigated in order to compare the results and to help clarify the oxidation mechanism of DNA.