Book of Abstracts: Albany 2009
June 16-20 2009
© Adenine Press (2008)
Effect of the Nonthermal Extra High Frequency Electromagnetic Waves on the Thermostability of Ligand-DNA Complexes
Dominant driving forces of the DNA minor groove binding ligands to A/T rich sites are the favorable increase in entropy due to the release of ordered water molecules from the spine of hydration and/or release of Na+ ions from the regions of higher ion density near the polyionic DNA molecules. Recently we have shown that irradiation of water-salt solutions by the nonthermal millimeter waves (ntMMW), referred to extremely high frequency (30-300 GHz) electromagnetic waves leads to the significant changes of spatial structure of water molecules. Therefore we assumed that the irradiation of ligand-DNA solution by the resonant of water structure frequency (50.3 GHz) will have the similar effect on the bulk solvent which will change the thermal stability of DNA-ligand complexes. To determine the effect on DNA-Hoechst 33258 stability caused by ntMMW, thermal denaturation experiments were performed to find out the changes of the melting temperature (Tm) values of investigated samples. It was shown that Tm of irradiated water solutions of DNA-H33258 complexes by ˜5°C greater than that of nonradiated complexes at the 2mM Na+, pH 6.9. We suggest that the registrated difference in thermal stability of the irradiated complexes is likely due to the disruption of the water network that run across the surface and the minor groove of DNA. The increase binding strength of the ligand with DNA is the result of significant contribution water network to binding partly through the enthalpy contribution of hydrating bonds and partly through entropic effects associated with desolvation of the reactants and salvation of the resulting complex.
Armen T. Karapetian1*