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Journal of Structural Chemistry

2009 year, number 5

CONFORMATIONAL CHANGES OF DNA Оі-IRRADIATED IN THE PRESENCE OF ALIPHATIC ALCOHOLS IN SOLUTION

S. V. Paston, V. V. Zamotin
Keywords: DNA conformation, quality of solvent, water?alcohol solutions, ? radiation, ОН radicals
Pages: 1007-1013

Abstract

The conformational changes of DNA in aqueous solutions containing ethanol and iso- and n-propanol having concentrations of 0-23 wt.% and ionic strength μ = 0.003 М NaCl and exposed to γ radiation at doses from 0 Gy to 30 Gy were studied by low-gradient viscosimetry and circular dichroism. The dependence of the specific volume (Vsp) of DNA on the radiation dose changed at different contents of alcohol. There is a critical concentration (Сcr) at which the structure of the mixed solvent is rearranged. The Vsp of DNA decreased as the radiation dose increased at Сalc = 12 wt.% < Сcr and increased at Сalc = 23 wt.% > Сcr. In both cases, the largest Vsp of DNA was observed in water−ethanol solutions. The secondary structure of the macromolecule in the systems corresponds to the В form. It was shown that the observed conformational changes in irradiated DNA at Сalc < Сcr and Сalc > Сcr could not be explained only by the ability of alcohols to intercept the ОН radicals formed in radiolysis of water.