Observations on X-ray-induced Radicals in Whole Bacteriophage and Phage Nucleic Acid

Abstract

ESR measurements on x-rayed purified bacteriophage of strain E. coli T2 and on DNA extracted from this phage have yielded the following main results: (1) The ESR absorption of DNA irradiated in vacuo at various temperatures showed a pronounced hyperfine structure if measured in vacuo at room temperature. (2) When DNA is subjected to increasing doses of x-rays in vacuo at room temperature saturation of radical concentration occurs at a few hundred kr. (3) The initial energy expenditure measured at room temperature after irradiation at various temperatures ranges between 8 and 30 ev per radical induced. (4) The ESR absorption of whole phage irradiated in vacuo at various temperatures is at room temperature equal to the absorption of phage-DNA plus that of a similar quantity of protein. (5) The dependence of radical concentration on dose in whole phage irradiated in vacuo at room temperature is equal to the dose-dependence of DNA, plus that of a similar quantity of protein.