Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas , SP 13083-859, Brazil.
Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany.
J Phys Chem B. 2017 Aug 3;121(30):7276-7283. doi: 10.1021/acs.jpcb.7b04934. Epub 2017 Jul 24.
The interaction of heavy charged particles with DNA is of interest for hadrontherapy and the aerospace industry. Here, a time-dependent density functional theory study on the interaction of a 4 keV proton with an isolated DNA base pair (bp) was carried out. Ehrenfest dynamics was used to study the evolution of the system up to about 193 fs. It was observed that the dissociation of the target occurs between 80 and 100 fs. The effect of bp linking to the DNA double helix was emulated by fixing the four O3' atoms responsible for the attachment. The bp tends to dissociate into its main components, namely, the phosphate groups, sugars, and nitrogenous bases. A central impact with an energy transfer of 17.9 eV only produces a base damage while keeping the backbone intact. An impact on a phosphate group with an energy transfer of about 60 eV leads to a backbone break at that site together with a base damage, and the opposite backbone site integrity is kept. As the whole system is perturbed during this collision, no atom remains passive. These results suggest that base damage accompanies all backbone breaks as the hydrogen bonds that keep bases together are much weaker that those between the other components of the DNA.
重带电粒子与 DNA 的相互作用是粒子疗法和航空航天工业感兴趣的问题。在这里，我们进行了一项关于 4 keV 质子与单个 DNA 碱基对（bp）相互作用的含时密度泛函理论研究。 Ehrenfest 动力学用于研究系统的演化，直到大约 193 fs。结果表明，靶的离解发生在 80 到 100 fs 之间。通过固定负责连接的四个 O3'原子，模拟了 bp 与 DNA 双螺旋的连接效应。bp 倾向于解离成其主要成分，即磷酸盐基团、糖和含氮碱基。只有能量转移为 17.9 eV 的中心冲击才会产生碱基损伤，而保持骨架完整。能量转移约为 60 eV 的磷酸盐基团的冲击会导致该位点的骨架断裂和碱基损伤，同时保持相反的骨架位点完整性。由于整个系统在碰撞过程中受到干扰，没有原子保持被动。这些结果表明，由于将碱基保持在一起的氢键比 DNA 其他成分之间的氢键弱得多，因此碱基损伤伴随着所有的骨架断裂。
