Binding of biologically important molecules to DNA, probed using electro-fluorescence polarization spectroscopy

Abstract

When small fluorescent tag molecules are bound with a single geometry to larger carrier molecules the fluorescence excited using polarized light may itself be partially polarized. If this is the case then alignment of the carrier molecules changes the fluorescence polarization. Electro-fluorescence polarization spectroscopy (EFPS) makes use of the fluorescence polarization changes which occur when the carrier molecules are aligned by an electric field. EFPS allows the determination of the binding geometry of the small tag molecules to the larger carrier molecules. In this study, EFPS has been used to probe the interactions between DNA and a series of chromosomal stains and anti-neoplastic (anti-cancer) agents. Results are presented for calf thymus DNA, treated with the dyes acridine orange, ethidium bromide, proflavine, Hoechst 33258, Hoechst 33342, 4′,6-diamidino-2-phenylindole and the anti-tumour agents, doxorubicin, daunomycin, actinomycin C and actinomycin V.