Application of An Ethidium Bromide Displacement Assay to Observe the Interaction Between DNA and Oxazole-based Copper Complexes

Ethidium bromide (EtBr) is a fluorescent dye that intercalates between the base pairs of double-stranded DNA, causing enhanced fluorescence. Displacement of the EtBr by a competitive binder causes quenching of the fluorescence. The data from EtBr displacement assays can be used to assess how strongly a molecule interacts with DNA, which is reported as an apparent binding constant, Kapp. The current study reports on the competitive DNA binding of three new oxazole-based copper(II) complexes. These oxazole-containing compounds are of interest due to their biological activity, including potential anticancer properties. We have found that these complexes competitively bind DNA, displacing the EtBr. Fluorescence intensity measurements were used to calculate the binding constants (Kapp) for each complex. The results of these studies will be presented along with a discussion of how EtBr displacement assays can be used to assess the magnitude of interaction of DNA targeting molecules.