title: Trapping of excess electrons at the microhydrated protonated amino groups in proteins.
abstract: We present a combined first-principles calculation and molecular dynamics simulation study of an excess electron (EE) in condensed phase of a microhydrated protonated amino group in proteins in this work. The protonated amino group, -NH(3)(+), is modeled by a CH(3)NH(3)(+) and an amount of water molecules are included to form various microhydrated CH(3)NH(3)(+) clusters, and the states and the dynamics of the trapped EE are analyzed. In addition to the localized and delocalized states observed, the N-H/O-H bond cleavage phenomena followed by escape of a H atom are also observed for some hydrated clusters in which the -NH(3)(+) group exposes on the surface of the cluster and directly participates in binding an EE. The state-to-state conversion is controlled by thermal motion of molecules in the clusters, and the cleavage of the N-H or the O-H bond and the H escape are determined by the binding modes of the EE. The H-escape nature could be attributed to the dissociation of the N-H or O-H bond induced by the trapped EE which transfers to their antibonding orbitals. This work provides a microscopical picture of the EE trapping at a microhydrated hydrophilic group in proteins, long-range electron migration, and the H-evolving mechanisms relevant for the lesions or damages of proteins or DNA. This is the first step in considering increasingly larger peptide fragments for further investigation of the detailed lesion/damage or charge migration mechanisms. Further work about this topic is underway.
authors.affiliation: The Center for Modeling & Simulation Chemistry, Institute of Theoretical Chemistry, Shandong University, Jinan, 250100, People's Republic of China.
authors.forename: Wenchao
authors.initials: W
authors.lastname: Li
authors.forename: Zhenwei
authors.initials: Z
authors.lastname: Zhang
authors.forename: Hongfang
authors.initials: H
authors.lastname: Yang
authors.forename: Xiuxiu
authors.initials: X
authors.lastname: Wu
authors.forename: Jinxiang
authors.initials: J
authors.lastname: Liu
authors.forename: Yuxiang
authors.initials: Y
authors.lastname: Bu
mesh_terms: D004247:DNA / Q000737:chemistry; D004583:Electrons; D057927:Hydrophobic and Hydrophilic Interactions; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D011506:Proteins / Q000737:chemistry*; D011522:Protons; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D011506:Proteins; D011522:Protons; D014867:Water; D004247:DNA