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

Iron oxidation in Escherichia coli bacterioferritin ferroxidase centre, a site designed to react rapidly with H2O2 but slowly with O2. Angew Chem Int Ed Engl. 2021 Jan 22;: Authors: Pullin J, Wilson MT, Clémancey M, Blondin G, Bradley JM, Moore GR, Le Brun NE, Lučić M, Worrall JAR, Svistunenko DA 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. PMID: 33482043 [PubMed - as supplied by publisher]
Source: Angewandte Chemie - Category: Chemistry Authors: Tags: Angew Chem Int Ed Engl Source Type: research