Multinuclear NMR Investigation of the NaDNA/Ethidium Bromide Anisotropic System

Abstract

A combined use of ³¹P, ²³Na, ²H and ¹⁷O NMR spectroscopies and polarized light microscopy has been employed to investigate the effect of the ethidium bromide (EB) binding on the liquid crystalline phase of concentrated double stranded DNA solutions. The optical textures and the ³¹P and ²³Na NMR spectra of the DNA anisotropic solutions show that the intercalation of EB induces significant modifications either in the arrangements of the DNA rods and the surrounding ionic atmosphere. On the contrary, no indication of significant changes of the orientational order of the water molecules around DNA emerges from the water ²H and ¹⁷O NMR spectra.