Study of complexes of Hoechst 33258 with poly(rA)-poly(rU) depending on various ionic strengths in the water-saline solution

Abstract

Comparative study of the complexes of groove-binding ligand Hoechst 33258 (H33258) with synthetic homopolynucleotides poly(rA)-poly(rU) and poly(dA)-poly(dT) has been carried out at various concentration ratios of r = ligand/nucleic acids (NA) and different ionic strengths of the water-saline solution 0.02, 0.04 and 0.1 M, using the method of UV-melting. It was revealed that the melting curves of the complexes of poly(dA)-poly(dT) with H33258 at the low concentrations of ligand are biphasic, which actually does not depend on the solution ionic strength. In the case of the complexes of poly(rA)-poly(rU)-H33258, the melting curves become quasi-biphasic only at the ionic strength 0.02 M and relatively high concentrations of the ligand. Differential melting curves (DMC) of the mentioned polynucleotides and their complexes with H33258 were obtained as well. DMC of poly(rA)-poly(rU) were found to be significantly wide at the ionic strengths of the solution 0.02 and 0.04 M and to show an intrinsic heterogeneity of double-stranded structure of this polynucleotide.

Communicated by Ramaswamy H. Sarma

Keywords:

• Synthetic polynucleotides
• groove binding ligand
• ionic strength
• melting curve
• melting parameters

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the RA MESCS Science Committee, in the frames of the research project №18T-1F030.