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  • Title: A short Fe-Fe distance in peroxodiferric ferritin: control of Fe substrate versus cofactor decay?
    Author: Hwang J, Krebs C, Huynh BH, Edmondson DE, Theil EC, Penner-Hahn JE.
    Journal: Science; 2000 Jan 07; 287(5450):122-5. PubMed ID: 10615044.
    Abstract:
    The reaction of oxygen with protein diiron sites is important in bioorganic syntheses and biomineralization. An unusually short Fe-Fe distance of 2.53 angstroms was found in the diiron (mu-1,2 peroxodiferric) intermediate that forms in the early steps of ferritin biomineralization. This distance suggests the presence of a unique triply bridged structure. The Fe-Fe distances in the mu-1, 2 peroxodiferric complexes that were characterized previously are much longer (3.1 to 4.0 angstroms). The 2.53 angstrom Fe-Fe distance requires a small Fe-O-O angle (approximately 106 degrees to 107 degrees). This geometry should favor decay of the peroxodiferric complex by the release of H2O2 and mu-oxo or mu-hydroxo diferric biomineral precursors rather than by oxidation of the organic substrate. Geometrical differences may thus explain how diiron sites can function either as a substrate (in ferritin biomineralization) or as a cofactor (in O2 activation).
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