Investigation of complexation of ethidium bromide with DNA by the method of Raman spectroscopy

Abstract

The investigation of complexation features of ethidium bromide (EB) with calf thymus DNA at the high and low ratios of biopolymer/ligand molar concentrations (P/D) was carried out using Raman spectroscopy and VIS-spectrophotometry. It was shown that EB binds to DNA with formation of two types of complexes: intercalation and exterior binding. The analysis of Raman spectra revealed that the amino groups of EB form the hydrogen bonds with acceptor atom groups of DNA in both types of complexes. A low extent of filling DNA structure by the ligand (P/D = 20) does not change the DNA B-form, while a high extent (P/D = 3) results in the conformation B-A transition.