DNA bifunctional intercalators. 2. Fluorescence properties and DNA binding interaction of an ethidium homodimer and an acridine ethidium heterodimer. Appendix: Numerical solution of McGhee and von Hippel equations for competing ligands

Citations Over TimeTop 10% of 1978 papers

Abstract

An ethidium homodimer and acridine ethidium heterodimer have been synthesized (Gaugain, B., Barbet, J., Oberlin, R., Roques, B. P., & Le Pecq, J. B. (1978) Biochemistry 17 (preceding paper in this issue)). The binding of these molecules to DNA has been studied. We show that these dimers intercalate only one of their chromophores in DNA. At high salt concentration (Na+ greater than 1 M) only a single type of DNA-binding site exists. Binding affinity constants can then be measured directly using the Mc Ghee & Von Hippel treatment (Mc Ghee, J. D., & Von Hippel, P. H. (1974) J. Mol. Biol. 86, 469). In these conditions the dimers cover four base pairs when bound to DNA. Binding affinities have been deduced from competition experiments in 0.2 M Na+ and are in agreement with the extrapolated values determined from direct DNA-binding measurements at high ionic strength. As expected, the intrinsic binding constant of these dimers is considerably larger than the affinity of the monomer (ethidium dimer K = 2 X 10(8) M-1; ethidium bromide K = 1.5 X 10(5) M-1 in 0.2 M Na+). The fluorescence properties of these molecules have also been studied. The efficiency of the energy transfer from the acridine to the phenanthridinium chromophore, in the acridine ethidium heterodimer when bound to DNA, depends on the square of the AT base pair content. The large increase of fluorescence on binding to DNA combined with a high affinity constant for nucleic acid fluorescent probes. In particular, such molecules can be used in competition experiments to determine the DNA binding constant of ligands of high binding affinity such as bifunctional intercalators.

Related Papers

• → Single Oligomer Spectra Probe Chromophore Nanoenvironments of Tetrameric Fluorescent Proteins(2006)20 cited
• → In Pseudomonas aeruginosa ethidium bromide does not induce its own degradation or the assembly of pumps involved in its efflux(2004)17 cited
• → Label Free Fluorometric Characterization of DNA Interaction with Cholate Capped Gold Nanoparticles Using Ethidium Bromide as a Fluorescent Probe(2014)5 cited
• → Interaction of ethidium bromide with whole and selectively deproteinized deoxynucleoproteins from calf thymus(1972)132 cited
• → Ethidium bromide resistance in a rat liver epithelial cell line: Association with enhanced drug efflux(1988)2 cited