Competitive Binding of Novel Cyanine Dye AK3-5 and Europium Coordination Complexes to DNA

Olga Zhytniakivska ,Anna Zabrudska ,Kateryna Vus ,Atanas Kurutos ,Valeriya Trusova ,Uliana Tarabara ,Galyna Gorbenko ,Todor Deligeorgiev

doi:10.26565/2312-4334-2019-3-08

Abstract

The present study was undertaken to assess the applicability of the novel trimethine cyanine dye AK3-5 as a competitive ligand for the antitumor agents, Eu(III) coordination complexes (EC), in the DNA-containing systems, using the displacement assay as an analytical instrument. The analysis of fluorescence spectra revealed a strong association of AK3-5 with nucleic acids, with the strength of interaction being higher for the double stranded DNA, compared to the single-stranded RNA. The binding parameters of the cyanine dye have been determined in terms of the McGhee & von Hippel neighbouring site-exclusion model and a classical Langmuir model. The AK3-5 association constant in the presence of DNA was found to be equal to 5.1×104 M-1, which is consistent to those of the well-known DNA intercalators. In turn, the binding of the cyanine to the RNA was characterized by a significantly lower association constant ( ~ 3.4×103 M-1) indicating either the external or “partially intercalated” binding mode. The addition of the europium complexes to the AK3-5-DNA system was followed by the fluorescence intensity decrease, with a magnitude of this effect being dependent on the EC structure. The observed fluorescence decrease of AK3-5 in the presence of europium complexes V7 and V9 points to the competition between the cyanine dye and antitumor drugs for the DNA binding sites. The dependencies of the AK3-5-DNA fluorescence intensity decrease vs. europium complex concentration were analyzed in terms of the Langmuir adsorption model, giving the values of the drug association constant equal to 5.4×104 M-1and 3.9×105 M-1 for the europium complexes V7 and V9, respectively. A more pronounced decrease of the AK3-5 fluorescence in the presence of V5 and V10 was interpreted in terms of the drug-induced quenching of the dye fluorescence, accompanying the competition between AK3-5 and Eu(III) complexes for the DNA binding sites. Cumulatively, the results presented here strongly suggest that AK3-5 can be effectively used in the nucleic acid studies and in the dye-drug displacement assays.

Highlights

Olga Zhytniakivska1*, Anna Zabrudska1, Uliana Tarabara1, Kateryna Vus1, Valeriya Trusova1, Galyna Gorbenko1, Atanas Kurutos2, Todor Deligeorgiev3
The present study was undertaken to assess the applicability of the novel trimethine cyanine dye AK3-5 as a competitive ligand for the antitumor agents, Eu(III) coordination complexes (EC), in the DNA-containing systems, using the displacement assay as an analytical instrument
In conclusion, the present study was focused on the possible application of the novel trimethine cyanine dye AK35 in the displacement assay using the potential antitumor agents, europium coordination complexes as competitive ligands

Summary

Introduction

Olga Zhytniakivska1*, Anna Zabrudska, Uliana Tarabara, Kateryna Vus, Valeriya Trusova, Galyna Gorbenko, Atanas Kurutos, Todor Deligeorgiev. Recent studies revealed that cyanine dyes can be effectively used for the high throughput screening of the drug-DNA interactions [10,11] The applicability of this class of fluorophores is based on the fact that they display a high affinity for nucleic acid double strands and a huge emission enhancement upon DNA binding. The aims of the present study were: i) to investigate the sensitivity of the novel trimethine cyanine, referred to here as AK3-5, to the double stranded DNA and single stranded RNA; ii) to estimate the parameters of the cyanine association with nucleic acids; iii) to analyze the binding mode of the novel dye; EEJP. The aims of the present study were: i) to investigate the sensitivity of the novel trimethine cyanine, referred to here as AK3-5, to the double stranded DNA and single stranded RNA; ii) to estimate the parameters of the cyanine association with nucleic acids; iii) to analyze the binding mode of the novel dye; EEJP. 3 (2019)

Objectives

Results

Conclusion