THE EFFECT OF NETROPSIN ON THE ELECTROCHEMICAL OXIDATION OF DNA AT A GRAPHITE ELECTRODE

The interaction of netropsin with calf thymus, Bacillus cereus and Micrococcus luteus DNA and with the RNA of phage f2 was studied by means of differential pulse voltammetry at a paraffin-wax-impregnated spectroscopic graphite electrode. The oxidation voltammetric peaks of double-helical calf thymus and B. cereus DNA were lowered when netropsin was added to the DNA solution. The peak corresponding to electro-oxidation of adenine residues was lowered more than that corresponding to electro-oxidation of guanine residues. Under the same experimental conditions the oxidation peaks of double-helical M. luteus DNA, double-helical RNA and thermally denatured samples of all DNA used were almost uninfluenced by the addition of netropsin. The results observed were explained by decreased flexibility of the segments to which netropsin was bound, and the specific binding of netropsin to the segments of double-helical DNA rich in adenine:thymine pairs.