| Numéro |
J. Phys. Colloques
Volume 47, Numéro C8, Décembre 1986
EXAFS and Near Edge Structure IV
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|---|---|---|
| Page(s) | C8-1155 - C8-1157 | |
| DOI | https://doi.org/10.1051/jphyscol:19868225 | |
J. Phys. Colloques 47 (1986) C8-1155-C8-1157
DOI: 10.1051/jphyscol:19868225
THE FORMATION, STRUCTURE AND DISSOLUTION OF THE FERRITIN IRON CORE STUDIED BY X-RAY ABSORPTION SPECTROSCOPY
E.C. THEIL1, D.E. SAYERS2, C.Y. YANG2, A. FONTAINE3 et E. DARTYGE31 Department of Biochemistry, North Carolina State University, Raleigh , NC 27695, U.S.A.
2 Department of Physics, North Carolina State University, Raleigh, NC 27695, U.S.A.
3 LURE, Université Paris-Sud, F-91405 Orsay Cedex, France
Abstract
Ferritin is the solution to the problem of rust in biological material. Polynuclear iron complexes of up to 4500 Fe(III) atoms reversibly form a hydrous ferric oxide core inside a hollow spherical protein coat (apoferrritin) that permits the controlled release of iron as needed by the organism. To study intermediates in formation of the iron core (A) and factors which may alter core structure (B), we used EXAFS. To study the factors which may influence the kinetics of iron core reduction and dissolution (C), we used dispersive x-ray absorption spectroscopy (DXAS). The results show (A) that the protein coat appears to control initiation and nucleation of the iron core; (B) that model iron core structures can be influenced by sulfate which appears to nucleare domains of hematite (Fe2O3) that coexist in the soluble complex with FeO.OH ; and (C) that the reduction of core Fe is influenced by buffer ions, suggesting that the availability of ferritin iron in vivo may be modulated by cytoplasmic changes in small ions.