RADIOLYTIC ATTACK OF DNA IS MODULATED BY DNA CONFORMATION - MONTE-CARLO SIMULATION

To study the influence of DNA structure on the probability of single s trand breaks induction by ionising radiations, the attack by OH radica ls is simulated by the Monte Carlo method. We have calculated the rela tive probabilities of OH radical reaction with all the reactive sites of: a) a DNA fragment in B form, containing the sequences AATT and AAA TT, and b) an intramolecular DNA quadruplex [G(4)(T(4)G(4))(3)] and th e corresponding duplex in B form. The results of our simulations are c ompared to the experimental values, and the effect of DNA structural v ariations on single strand breaks yield is discussed.