Interaction of ethidium bromide with DNA: effect of LiCl and ethylene glycol

Abstract

The interaction of the intercalating dye ethidium bromide with several native and synthetic polydeoxyribonucleic acids has been studied by means of circular dichroic spectra. The CD of DNA-ethidium bromide complexes in the 290-360 nm region is characterized, especially at high salt and at high ethylene glycol content, by positive and negative bands near 308 nm and 295 nm, respectively. These dye associated CD bands are unaffected by the addition of LiCl or ethylene glycol, suggesting that the relative conformation of dye and neighboring base pairs does not change when the conformation of the rest of the DNA changes.