The interaction of DNA with dopamine by spectroscopic and electrochemical methods.

It has recently been reported that dopamine may show some biological activities in antitumor and cell apoptosis. We have thoroughly investigated the interaction between dopamine and DNA by CD, UV, fluorescence and electrochemical methods. The results of spectroscopic measurements have indicated that a binding event occurs in a dopamine-DNA system. Besides the electronstatic interaction between a negatively charged DNA molecule and a positively charged dopamine molecule, other binding modes, such as hydrogen-bond and intercalation may also exist in this system. The interaction parameters, including the equilibrium constant and binding numbers, were estimated by an electrochemical method based on the redox current and formal potentials. Both of the two calculation methods showed that the 1:1 type of complex was formed in the dopamine-DNA system and that its equilibrium constant was about 5.85 x 10(6) M(-1). Based on the results of UV, fluorescence and electrochemical experiments in the present study, dopamine may be employed as an effective probe for a DNA assay.