Iron Oxidation in Escherichia coli Bacterioferritin Ferroxidase Centre, a Site Designed to React Rapidly with H2 O2 but Slowly with O2.
Angew Chem Int Ed Engl
; 60(15): 8361-8369, 2021 04 06.
Article
em En
| MEDLINE
| ID: mdl-33482043
ABSTRACT
Both O2 and H2 O2 can oxidize iron at the ferroxidase center (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 Fe2+ , was exposed to O2 or H2 O2 . We show that O2 binds di-Fe2+ FC reversibly, two Fe2+ ions are oxidized in concert and a H2 O2 molecule is formed and released to the solution. This peroxide molecule further oxidizes another di-Fe2+ FC, at a rate circa 1000 faster than O2 , ensuring an overall 14 stoichiometry of iron oxidation by O2 . Initially formed Fe3+ can further react with H2 O2 (producing protein bound radicals) but relaxes within seconds to an H2 O2 -unreactive di-Fe3+ form. The data obtained suggest that the primary role of EcBfr in vivo may be to detoxify H2 O2 rather than sequester iron.
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Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Oxigênio
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Proteínas de Bactérias
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Ceruloplasmina
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Grupo dos Citocromos b
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Escherichia coli
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Ferritinas
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Peróxido de Hidrogênio
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Ferro
Idioma:
En
Revista:
Angew Chem Int Ed Engl
Ano de publicação:
2021
Tipo de documento:
Article
País de afiliação:
Reino Unido