THERMODYNAMIC INVESTIGATION OF METHYLENE BLUE COMPLEXES WITH DNA

Abstract

The melting of DNA–methylene blue (MB) complexes has been carried out at 0.002 M and 0.02 M Na⁺ concentration. The values of melting parameters – melting temperature and melting interval width were obtained in concentration ratio change interval r=[ligand]/[DNA] – 0<r≤0.33. It was revealed that melting interval width change of complexes depending on ligand concentration arises at 0.02 M Na⁺ and r≤0.1 and gets out on plateau at r>0.1, while at 0.002 M Na⁺ this dependence acquires bell-like form. The increase of the interval of melting temperature was revealed at mentioned ionic strengths of solution depending on ligand concentration.