Albany 2015:Book of Abstracts
June 9-13 2015
©Adenine Press (2012)
The Binding Mechanisms of Methylene Blue with DNA
The melting of DNA and its complexes with methylene blue (MB) at 0.002M and 0.02M Na+ ionic strengths of the solution in the concentration ratio changing interval 0<r≤0.33, where r = [ligand]/[DNA], has been carried out. It was revealed that the change of the melting interval width (δΔT) of the complexes depending on ligand concentration at 0.02M Na+ increases at r≥0.1 and gets to the saturation at r≥0.1, while at 0.002M Na+ , this parameter acquires a bell-like shape depending on ligand concentration. The change of melting temperature Tm increases with ligand concentration enhancement at the mentioned ionic strengths of the solution, moreover at 0.002M ionic strength of the solution the melting temperature is significantly higher than at 0.02M Na+ (Vardevanyan, Antonyan et al., 2013). Comparison of the obtained data with analogous ones obtained for DNA-EtBr complexes permits to conclude that at low ionic strengths of the solution MB binds to DNA by intercalation, semi-intercalation as well as electrostatic mechanisms. At the same time at 0.02M ionic strength of the solution, MB binds to DNA only by semi-intercalation and electrostatic modes. It was also shown that at 0.02M ionic strength of the solution the melting interval width change of MB complexes with DNA enhances depending on the increase of GC-sequence content in its. Therefore the obtained data indicate that MB as EtBr may bind to DNA by different mechanisms. Furthermore if in the case of EtBr the intercalation takes place at not only low (0.002M) but also relatively high ionic strengths of the solution (>0.002M), in the case of MB at 0.02M ionic strength of the solution the intercalation mode is not performed. These data also reveal the preference of ligand molecules to GC-sequences at intercalation or semi-intercalation.
P.O. Vardevanyan, A.P. Antonyan, M.A. Parsadanyan, M.A. Shahinyan, L.A. Hambardzumyan, Minasyants, A.T. Karapetian (2013). Spectroscopic investigation of methylene blue binding to DNA. Journal of Biomolecular Structure and Dynamics 31, 1-139, Supplement, Book of Abstracts. Albany 2013: The 18th Conversation, 59.
Ara P. Antonyan
Department of Biophysics