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Iron oxidation in Escherichia coli bacterioferritin ferroxidase centre, a site designed to react rapidly with H2O2 but slowly with O2

Pullin, Jacob and Wilson, Michael T and Clémancey, Martin and Blondin, Geneviève and Bradley, Justin M and Moore, Geoffrey R and Le Brun, Nick E and Lučić, Marina and Worrall, Jonathan AR and Svistunenko, Dimitri A (2021) 'Iron oxidation in Escherichia coli bacterioferritin ferroxidase centre, a site designed to react rapidly with H2O2 but slowly with O2.' Angewandte Chemie International Edition, 60 (15). 8361 - 8369. ISSN 1433-7851

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Abstract

Both O 2 and H 2 O 2 can oxidise iron at the ferroxidase centre (FC) of Escherichia coli bacterioferritin (EcBfr) but mechanistic details of the two reactions need clarification. UV‐vis, EPR and Mössbauer spectroscopies have been used to follow the reactions when apo‐EcBfr, pre‐loaded anaerobically with Fe 2+ , was exposed to O 2 or H 2 O 2 . We show that O 2 binds di‐Fe 2+ FC reversibly, two Fe 2+ ions are oxidised in concert and a H 2 O 2 molecule is formed and released to solution. This peroxide molecule further oxidises another di‐Fe 2+ FC, at a rate ~1000 faster than O 2 , ensuring an overall 1:4 stoichiometry of iron oxidation by O 2 . Initially formed Fe 3+ can further react with H 2 O 2 (producing protein bound radicals) but relaxes within seconds to an H 2 O 2 ‐unreactive di‐Fe 3+ form. The data obtained suggest that the primary role of EcBfr in vivo may be to detoxify H 2 O 2 rather than sequester iron.

Item Type: Article
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Elements
Date Deposited: 06 Apr 2021 08:40
Last Modified: 06 Apr 2021 08:40
URI: http://repository.essex.ac.uk/id/eprint/30150

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