Comparison of direct DNA strand break simulated with different DNA models.

In Monte Carlo simulation of DNA damage, the geometric model of DNA is of great importance. To study the influence of DNA model on the simulation of DNA damage, three DNA models were utilised in this paper. They were a volume model and two atomic models with different parameters. A direct DNA strand break induced by low-energy electrons was simulated, respectively, with the three models. The results show that most of the energy depositions in the DNA segments do not lead to strand breaks. The simple single-strand break (SSB) tends to be the predominant damage type, and the contribution of complex double-strand break (DSB) to the total DSB cannot be neglected. Among the yields of all the three DNA target models applied here, the yields of the volume model are the highest, the yields of the atomic model with double van der Waals radii (r) take the second place, whereas the yields of the atomic model with single r come last. On average, the ratios of SSB yields are approximately equivalent to the corresponding ratios of the models' volume. However, there seems to be no clear relationship between the DSB yields and the models' volume.