Atomistic Simulation Centre , Queen's University Belfast , Belfast BT7 1NN , U.K.
Department of Physics , Nanjing University of Information Science and Technology , Nanjing 210044 , China.
J Phys Chem B. 2019 Feb 21;123(7):1537-1544. doi: 10.1021/acs.jpcb.8b11621. Epub 2019 Feb 12.
Ionizing radiation can excite the cellular medium to produce secondary electrons that can subsequently cause damage to DNA. The damage is believed to occur via dissociative electron attachment (DEA). In DEA, the electron is captured by a molecule in a resonant antibonding state and a transient negative ion is formed. If this ion survives against electron autodetachment, then bonds within the molecule may dissociate as energy is transferred from the electronic degrees of freedom into vibrational modes of the molecule. We present a model for studying the effect that transferring kinetic energy into the vibrational modes of a molecule in this way has on a DNA nucleobase. We show that when the base is in an aqueous environment, dissociation is affected by interactions with the surrounding water molecules. In particular, hydrogen bonding between the nucleobase and the solvent can suppress the dissociative channel.
电离辐射可以激发细胞介质产生次级电子，这些电子随后可能会对 DNA 造成损伤。这种损伤据信是通过离解电子俘获（DEA）发生的。在 DEA 中，电子被处于共振反键态的分子捕获，并形成瞬态负离子。如果这个离子能够抵抗电子自离解，那么分子内的键就可能会解离，因为能量从电子自由度转移到分子的振动模式中。我们提出了一个模型，用于研究将动能以这种方式转移到分子的振动模式中对 DNA 碱基的影响。我们表明，当碱基处于水相环境中时，其解离会受到与周围水分子相互作用的影响。特别是，碱基与溶剂之间的氢键可以抑制离解通道。
