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Albany 2019: 20th Conversation - Abstracts

category image Albany 2019
Conversation 20
June 11-15 2019
Adenine Press (2019)

Study of three-component system, consisted of DNA complexes with ligands of different type

The joint binding of intercalators EtBr and AO, intercalator EtBr and semi-intercalator MB, intercalator EtBr and groove-binding compound Hoechst 33258 (H33258) with DNA has been studied using UV melting method at ionic strengths of the solution 2 mM and 20 mM. The values of melting temperature (Tm) and melting interval width (ΔT) of DNA-ligand complexes were obtained and based on them the values of changes of these parameters – δ(1/Tm) and δ(ΔT/Tm2) on ligand concentrations were determined. The obtained results indicate that at the joint binding of two different ligands with DNA, the solution ionic strength has a determining effect of on their binding modes. Meanwhile, the joint interaction of intercalator and non-intercalator or two intercalators with DNA is not a simple sum of their separate binding. Moreover, at their joint interaction with DNA a competition between them emerges. These results also indicate that the joint interaction of two different multimodal ligands with DNA is not a result of binding by at least two modes of one type of ligand (Karapetian et al, 2016).

Results of the experimental studies of DNA complexes with two different ligands reveal that the immediate binding of any type of the ligand with DNA leaves a separate effect on its thermodynamic characteristics, though the joint impact of two (and, probably, more) different ligands is not a simple sum of such influences. Moreover, in the certain degree, the joint effect of two ligands on thermodynamic characteristics of DNA helix-coil transition is possible to consider as the effect of “generalized” ligand, which shows intrinsic properties for the latter (Nafisi et al, 2007). It is also obvious that the long polymer chain of DNA acts as one integer, since even at non-relevant concentrations of two different ligands, when the regions between these compounds outlying from each other are filled by molecules, it behaves not as in the case of separate binding at the same concentrations. This fact may elucidate some questions, connected to DNA functioning regulation (initiation, inhibition, expression of genes) in cell. Nonetheless, the obtained data do not put in a claim for absoluteness, since it cannot be excluded the additive effect of two different ligands on parameters of DNA conformational transitions, which may also have a certain biological value for DNA functioning regulation.

References

    Karapetian, A.T., Grigoryan, Z.A., Mamasakhlisov, Y.S., Minasyants M.V. &Vardevanyan, P.O. (2016). Theoretical treatment of helix-coil transition of complexes DNA with two different ligands having different binding parameters. J. Biomol. Struct. Dyn. 34, 198-202. DOI: 10.1080/07391102.2015.1010584.

    Nafisi, Sh, Saboury, A.A., Keramat, N., Neault, J.-F., Tajmir-Riahi & H.-A. (2008). Stability and structural features of DNA intercalation with ethidium bromide, acridine orange and methylene blue. Journal of Molecular Structure 827, 35-43.

Ara P. Antonyan
Marine A. Parsadanyan
Narek H. Shahnazaryan
Poghos O. Vardevanyan*

Department of Biophysics
Yerevan State Univbersity
Yerevan, Armenia

Ph: (+37460) 710522
Email: p.vardevanyan@ysu.am