[The role of ethanol during gamma-irradiation of water-salt DNA solutions]

In this work we had assumed to clarify the role of the water structure in the process of the radiation damage of DNA. It is known that the aliphatic alcohols stabilize the water structure until the critical concentration. In this connection we have analyzed the changes of the long- and short-distance interactions in the DNA irradiated in the water-ethanol solutions with various concentration of the ethanol and ions of metal. It was shown that as the water structure becomes more stable the conformational damages in the DNA are decreasing and finally at the some concentration of the alcohol in the irradiated solution the damages disappear. By the achieving of the alcohol concentration which lead to the destruction of the water structure the radiation results in the same changes of the considered parameters as in the case of the DNA irradiated in the water-salt solution with ethanol. The analyses of the experimental data allow us to conclude that the radiation destroys the structure of the water and thus helps the positive ions from the solution to come nearer to the DNA, to say, the radiation reduce intramolecular electrostatic interactions. This concept allows us to explain the observed changes of intrinsic viscosity and the difference in the polarizabilities of the DNA in the process of the radiation damage.