Analysis of Spectral properties of DNA complexes with biological active dyes in vitro to establish the molecular mechanism of their action
Nina Kasyanenko1, Boris Paponov2, Ariana Chuvakina1 , Vladimir Bakulev1
1Saint Petersburg State University, Saint Petersburg, Russia
2Pavlov University, Saint Petersburg, Russia
Abstract
DNA complexes with thiazolopyrimidine dyes ( C17H18N3S+ClO4- (1), C26H27N4S+ ClO4- (2) , C18H20N3S+ClO4M (3)) were examined in vitro. Such dyes can be regarded as potential bases for new drugs, including anticancer activity, bioanalysis, cell imaging, etc. DNA is the main target for the most effective antitumor drugs. Different binding modes with DNA for a certain compound may appear depending on its concentration in DNA solution and on environmental conditions such as pH and ionic strength. Usually, the identifying the mode of binding of a dye to DNA is not an easy task. A common starting point for such analysis is the study of spectral properties with varying the ratio of the dye to DNA base pairs molar concentrations in a solution. We used also circular dichroism and viscometry. The last gives the information about a global structural reorganization of DNA molecule in complexes. Positively charged ligands can easy form the biologically significant complexes with DNA due to the unconditional first step of interaction via its electrostatic attraction to the negatively charged DNA phosphates. The influence of the solution ionic strength on the structure of the formed complexes is considered in detail. Calf thymus DNA (Sigma-Aldrich) with M = 18 000 base pairs was used. It was shown that in water-salt solutions without DNA the molecules of compound 3 associate to dimers of H- and J-types. In DNA solutions the complexes of different structures with intercalation or minor-groove binding were observed. The molecular mechanism of DNA interaction with compounds is discussed.
Speaker
Nina Kasyanenko
Saint Petersburg State University
Россия
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