Configurational Aspects of DNA, Histone and Reconstituted Nucleohistone before and after Gamma Irradiation

The absorption value for reconstituted DNH is less than that of DNA in the X-peak in the unirradiated state. For Y-peak, intensity of absorption is lower for DNA and those for H₃-histone and reconstituted DNH am same. With increasing pH, hyperchromicity of H₃-histone slowly increases indicating unfolding of peptide bonds with increasing pH. Consideration of Y/X ratio reveals that the degree of denaturation by gamma irradiation has been more for DNA as compared to reconstituted DNH for the same irradiation dose. Thus protection of DNA against radiation has been noted due to presence of H₃-histone. Denaturation with radiation has been found to be more for DNH reconstituted after irradiation as compared to that of DNH reconstituted before irradiation.