Interactions of Dissolved dsDNA with Intercalating Drug by Anodic Voltammetry and Spectroscopy. Influence of pH

The interactions of C-1305 (5-dimethylaminopropylamino-8-hydroxy-6H-v-triazolo[4,5,1-de]acridin-6-one) with DNA were studied using differential pulse voltammetry and UV-vis spectroscopy. C-1305 interacts with dsDNA in two ways: by intercalation and by binding to the minor-groove. For the intercalation at physiological pH (7.4) the values of the binding constant, K(1), and the binding-site size, n(1), equal 3.36 x 10(5) M(-1) and 2.5, respectively. For the weak interactions the K(2) and n(2) parameters equal 0.18 x 10(5) M(-1) and 4. In the presence of excess NaCl the weak interactions do not vanish, therefore they are assigned to the minor groove binding. Substantial and complex is the influence of pH.