Mechanistic insights into the electron attachment process to guanosine in the presence of arginine

Abstract

The attachment of low-energy electrons (LEEs) to the DNA biomolecules leads to irreversible damage. However, the behavior of this interaction can be influenced by the presence of amino acids. Herein, we have delved into the mechanism of electron attachment to the guanosine in the presence of arginine. The study used combined molecular dynamics (MD) simulations and quantum mechanics/molecular mechanics (QM/MM) approaches to collect and optimize the geometries having hydrogen-bonds (H-bonds) between guanosine and arginine, respectively, followed by atom centered density matrix propagation (ADMP) simulations to assess the electron attachment ability of guanine with and without arginine. The vertical detachment energy (VDE) and natural population analysis (NPA) suggest that the electron attached to guanosine is more readily due to the H-bonds between guanosine and arginine. The singly occupied molecular orbitals (SOMOs), VDE, and NPA from ADMP results corroborated the idea that in the presence of arginine electron effectively attached to guanosine moiety while the auto detachment process becomes less probable in the case of arg-guanosine (two-H bonds). However, in the presence of arginine, the dissociative electron attachment (DEA) process for guanosine is exothermic, while in the absence of arginine, it is endothermic. This study provides new insight into the process of radiation damaging biological systems by elucidating the DEA to DNA subunits in the presence of amino acids, paving the way for a deeper understanding of radiation-induced damage in biological systems.