A comparative pulse radiolysis study on DNA's of various molecular masses under anoxic and salt-free conditions, based on conductivity measurements

Abstract

OH radical attack on various molecular mass DNA molecules in aqueous solutions in O2-free, N2O-saturated solutions at room temperature and with lower doses have been studied. The two phenomena, resulting in a negative and a positive conductivity build-up under a short electron pulse (0.4–1 μs), are discussed in the light of their dependence on the pH, dose rate, concentration and temperature. The positive conductivity build-up observed at lower concentrations of DNA and higher doses is attributed to a degradation process resulting in ssb formation and liberation of counter ions, whereas the negative conductivity build-up at the higher concentrations of DNA and relatively lower doses is attributed to an intermolecular reaction, resulting in cross-links and condensation of the counter ions. The dependence of the applied potential (20–100 V) on the rate constant and conductivity build-up for both processes are shown.