Denaturing effect of x-irradiation on deoxyribonucleic acid aqueous solutions: An immunochemical study

The denaturation of calf thymus DNA aqueous solutions following x-ray radiation (x-DNA) has been investigated with the help of a rabbit antidenatured DNA antiserum. These antibodies were shown to recognize exclusively single-stranded DNA determinants on DNA molecule in double immunodiffusion analysis. By means of this method it was possible to demonstrate that increasing numbers of single-stranded DNA determinants were formed in DNA solutions exposed to increasing doses of radiation. The rabbit serum appeared to be a highly sensitive reagent (0.5 mug/ml of single-stranded DNA) capable of detecting DNA denaturation when low ionizing doses were used and when only minor changes in DNA physico-chemical parameters were measurable. Antigenic comparison between x-DNA and heat-denatured DNA demonstrated that antigenic determinants are shared by the two molecules. The possible application of immunochemical methods to the study of nucleic acid denaturation by different physical and chemical agents is discussed.