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Issue 40, 2015
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Excess electron reactivity in amino acid aqueous solution revealed by ab initio molecular dynamics simulation: anion-centered localization and anion-relayed electron transfer dissociation

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Abstract

Studies on the structure, states, and reactivity of excess electrons (EEs) in biological media are of great significance. Although there is information about EE interaction with desolvated biological molecules, solution effects are hardly explored. In this work, we present an ab initio molecular dynamics simulation study on the interaction and reactivity of an EE with glycine in solution. Our simulations reveal two striking results. Firstly, a pre-solvated EE partially localizes on the negatively charged –COO group of the zwitterionic glycine and the remaining part delocalizes over solvent water molecules, forming an anion-centered quasi-localized structure, due to relative alignment of the lowest unoccupied molecular orbital energy levels of potential sites for EE residence in the aqueous solution. Secondly, after a period of anion-centered localization of an EE, the zwitterionic glycine is induced to spontaneously fragment through the cleavage of the N–Cα bond, losing ammonia (deamination), and leaving a ˙CH2–COO anion radical, in good agreement with experimental observations. Introduction of the same groups (–COO or –NH3+) in the side chain (taking lysine and aspartic acid as examples) can affect EE localization, with the fragmentation of the backbone part of these amino acids dependent on the properties of the side chain groups. These findings provide insights into EE interaction mechanisms with the backbone parts of amino acids and low energy EE induced fragmentation of amino acids and even peptides and proteins.

Graphical abstract: Excess electron reactivity in amino acid aqueous solution revealed by ab initio molecular dynamics simulation: anion-centered localization and anion-relayed electron transfer dissociation

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Publication details

The article was received on 27 Jun 2015, accepted on 01 Sep 2015 and first published on 15 Sep 2015


Article type: Paper
DOI: 10.1039/C5CP03720D
Citation: Phys. Chem. Chem. Phys., 2015,17, 26854-26863

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    Excess electron reactivity in amino acid aqueous solution revealed by ab initio molecular dynamics simulation: anion-centered localization and anion-relayed electron transfer dissociation

    X. Wu, L. Gao, J. Liu, H. Yang, S. Wang and Y. Bu, Phys. Chem. Chem. Phys., 2015, 17, 26854
    DOI: 10.1039/C5CP03720D

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