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Computational Studies of Electron Transfer in Multi-Heme Proteins

Jiang, Xiuyun; (2019) Computational Studies of Electron Transfer in Multi-Heme Proteins. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Multi-heme proteins are fascinating biomolecules that bind several redox-active heme cofactors in close distance to shuttle electrons across the bacterial membrane. Yet, the kinetics and time scales on which these electron transfer (ET) events occur is not well known and difficult to probe experimentally. The central aim of this thesis is to compute and to quantify heme-heme ET rate constants and electron flux through solvated multi-heme proteins. To this end, density functional theory and molecular dynamics simulation are deployed to compute heme-heme ET parameters in the framework of (non-adiabatic) Marcus theory, the central theory underlying such ET events. Three ubiquitous multi-heme proteins have been studied, which bind 4 and 10 heme cofactors. Our calculations revealed that electron transfer through these proteins is strongly enhanced by cysteine side chains that are inserted in the space between heme groups. We believe this to be a general design principle in this family of proteins for acceleration of ET steps that would otherwise be too slow for biological respiration. Our computational protocol has been verified via comparing our predicted time scale of heme-heme ET with the corresponding ET rate constant measured from pump-probe spectroscopy. The maximum, protein-limited electron flux is ≈ 10^5 - 10^6 s^-1. Such efficiency in long-range electron transfer indicates that multi-heme proteins are promising candidates for biological nano-electronic devices.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Computational Studies of Electron Transfer in Multi-Heme Proteins
Event: UCL
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2019. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10087886
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