A fluorescent complex between ethidium bromide and nucleic acids

At high salt concentrations, ethidium bromide (EB) is shown to form a fluorescent complex with helical polynucleotides which has a strikingly enhanced fluorescence quantum yield. In this paper we present evidence that formation of this complex (complex I) ia specific for base-paired regions either in DNA, RNA or RNA: DNA hybrids, and that the basis of this specificity is intercalation of the dye between base pairs. At low salt concentrations a...