Study of ethidium bromide interaction peculiarities with DNA

Abstract

The helix-coil transition of DNA-ethidium bromide complexes in an interval of ionic strength of 2.0 × 10-3 M ≤ μNa+ ≤ 2.0 × 10-2 M has been investigated. It has been revealed that at the certain high ligand-DNA ratios (rb) the transition interval of the complex - (ΔT) becomes equal to that of DNA itself (ΔT0). It has been shown that the values of rb at which δΔT=ΔT-ΔT0=0 depends on ionic strength of a solution. Further increasing of ligand concentration leads to its conversion from stabilizer into the destabilizer of the double-stranded DNA.