Investigating Mechanisms of Radiation-Induced DNA Damage Using Low-Energy Photons

Central to any mechanistic biophysical model of radiation damage to DNA is the relationship between the amount and distribution of energy deposited in the DNA helix and the subsequent production of DNA damage. It is now clear from a number of studies that the minimum energy required to produce bond breaks in DNA is significantly lower than might be expected. For example, some biophysical models have assumed that it takes several 10s of eV to produce a double-strand break in DNA. However, using low-energy photons, we have shown that energy depositions as low as 7 eV can induce double-strand break and that this is enhanced when the DNA is hydrated, showing that free radical damage is also important.