Radiolytic attack of DNA is modulated by DNA conformation. Monte Carlo simulation

To study the influence of DNA structure on the probability of single strand breaks induction by ionising radiations, the attack by OH radicals is simulated by the Monte Carlo method. We have calculated the relative probabilities of OH radical reaction with all the reactive sites of: a) a DNA fragment in B form, containing the sequences AATT and AAATT, and b) an intramolecular DNA quadruplex [G(4)(T(4)G(4))(3)] and the corresponding duplex in B form. The results of our simulations are compared to the experimental values, and the effect of DNA structural variations on single strand breaks yield is discussed.