Conformational changes of DNA γ-irradiated in the presence of aliphatic alcohols in solution

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 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 ( V sp ) of DNA on the radiation dose changed at different contents of alcohol. There is a critical concentration ( C cr ) at which the structure of the mixed solvent is rearranged. The V sp of DNA decreased as the radiation dose increased at C alc = 12 wt.% < C cr and increased at C alc = 23 wt.% > C cr . In both cases, the largest V sp of DNA was observed in water ethanol solutions. The secondary structure of the macromolecule in the systems corresponds to the form. It was shown that the observed conformational changes in irradiated DNA at C alc < C cr and C alc > C cr could not be explained only by the ability of alcohols to intercept the radicals formed in radiolysis of water.