Investigation of DNA Damage Induced by Proton and Gamma Radiation
In this study, we compared the effects of gamma and high-energy proton (1000 MeV) radiation on DNA in aqueous saline solutions (5 mM and 150 mM NaCl) at doses of 30 Gy and 50 Gy. We used spectral methods (ultraviolet absorption method, spectrophotometric methods for nucleic acid quantification, spectrophotometric assay and melting temperature used for DNA characterization, circular dichroism) for the estimation of the number of damaged nitrogenous bases and damage of a secondary DNA structure. It was found that under these conditions, proton radiation causes more severe destruction of nitrogenous bases and the secondary DNA structure than an exposure to gamma rays at the same dose. In DNA irradiated with protons, the formation of crosslinks is possible, the probability for crosslinking increases with the rise of the ionic strength of the irradiated solution.