Novel DNA Interacting Molecules with Potentially Two Mode Binding Ability.

Abstract

The binding study and spectral behavior of novel DNA interacting dyes, bis(vinylpyridinium) benzene derivatives, are reported. Implantation of a extended π-electron moiety into a viologen molecule has lead to the preparation of a series of dicationic dyes with fluorescent properties and potential capability of interacting with DNA by both groove binding and intercalation mode. Drug-DNA interactions were investigated by UV-VIS absorption and fluorescence titration, and circular dichroism measurements. There were no clear isosbestic points in titration data which suggested complex interaction of drugs with DNA. As a tentative explanation of these results, we believe that dye molecules aggregate or intercalate with DNA at lower P/D ratios (DNA to dye concentration) and undergo redistribution in the minor groove at higher P/D ratios. The groove binding mode was supported by presence of induced CD spectra of dyes in the presence of AT sequence containing oligonucleotides. The most pronounced groove binding was observed for the curved m-bis(vinylpyridinium) benzene derivative. Such bimodal behavior may be of great importance for the further application of dyes since DNA sequence selectivity can also serve as valuable tool for the development of base selective DNA probing methods.