Peculiarities of the Binding of Some Small Ligands to DNA

Abstract

The comparative study of the interaction of ethidium bromide, acridine orange, and isoquinoline alkaloids such as sanguinarine and berberine with DNA in aqueous solutions using the optical spectroscopy methods is presented. The dependences of the spectral characteristics of ligands on the concentration ratio P/D between the DNA base pairs and ligands molecules in solutions are considered. The character of binding is found to depend on P/D. The parameters of the binding with DNA are determined for the external binding and the intercalation, by using the modified Scatchard and McGhee–von Hippel equations. The influence of a ligand form on binding ways is shown.

Keywords:

• DNA
• ligand
• binding equations
• intercalation
• external binding

Acknowledgments

The authors are grateful to V. Kosach for the help in the recording of the absorption and fluorescence spectra and L. Zaika (Institute of Molecular Biology and Genetics of the NASU, Kyiv) for the specimens.