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Title: Iron(III) clusters bound to horse spleen apoferritin: an X-ray absorption and Moessbauer spectroscopy study that shows that iron nuclei can form on the protein

Abstract

Ferritin is a complex of a hollow, spherical protein and a hydrous, ferric oxide core of less than or equal to4500 iron atoms inside the apoprotein coat; the apoprotein has multiple binding sites for monoatomic metal ions, e.g., Fe(II), V(IV), Tb(III), that may be important in the initiation of iron core formation. In an earlier study the authors observed that the oxidation of Fe(II) vacated some, but not all, of the metal-binding sites, suggesting migration of some Fe during oxidation, possibly to form nucleation clusters; some Fe(III) remained bound to the protein. Preliminary extended X-ray absorbance fine structure (EXAFS) analysis of the same Fe(III)-apoferritin complex showed an environment distinct from ferritin cores, but the data did not allow a test of the Fe cluster hypothesis. In this paper, with improved EXAFS data and with Moessbauer data on the same complex formed with /sup 57/Fe, they clearly show that the Fe(III) in the distinctive environment is polynuclear. Moreover, the arrangement of atoms is such that Fe(III) atoms appear to have both carboxylate-like ligands, presumably from apoferritin, and oxo bridges to the other iron atoms. Thus the protein provides sites not only for initiation but also for nucleation of the iron core.more » Sites commodious enough and with sufficient conserved carboxylate ligands to accommodate such a nucleus occur inside the protein coat at the subunit dimer interfaces. Such Fe(III)-apoferritin nucleation complexes can be used to study the properties of the several members of the apoferritin family.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
North Carolina State Univ., Raleigh
OSTI Identifier:
6521688
Resource Type:
Journal Article
Journal Name:
Biochemistry; (United States)
Additional Journal Information:
Journal Volume: 26:2
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; FERRITIN; ABSORPTION SPECTRA; MOLECULAR STRUCTURE; X-RAY SPECTROSCOPY; HORSES; IRON 57; IRON OXIDES; SPLEEN; ANIMALS; BODY; CHALCOGENIDES; COMPLEXES; EVEN-ODD NUCLEI; INTERMEDIATE MASS NUCLEI; IRON COMPLEXES; IRON COMPOUNDS; IRON ISOTOPES; ISOTOPES; MAMMALS; METALLOPROTEINS; NUCLEI; ORGANIC COMPOUNDS; ORGANS; OXIDES; OXYGEN COMPOUNDS; PROTEINS; SPECTRA; SPECTROSCOPY; STABLE ISOTOPES; TRANSITION ELEMENT COMPLEXES; TRANSITION ELEMENT COMPOUNDS; VERTEBRATES; 550601* - Medicine- Unsealed Radionuclides in Diagnostics; 550602 - Medicine- External Radiation in Diagnostics- (1980-)

Citation Formats

Yang, C, Meagher, A, Huynh, B H, Sayers, D E, and Theil, E C. Iron(III) clusters bound to horse spleen apoferritin: an X-ray absorption and Moessbauer spectroscopy study that shows that iron nuclei can form on the protein. United States: N. p., 1987. Web. doi:10.1021/bi00376a023.
Yang, C, Meagher, A, Huynh, B H, Sayers, D E, & Theil, E C. Iron(III) clusters bound to horse spleen apoferritin: an X-ray absorption and Moessbauer spectroscopy study that shows that iron nuclei can form on the protein. United States. https://doi.org/10.1021/bi00376a023
Yang, C, Meagher, A, Huynh, B H, Sayers, D E, and Theil, E C. 1987. "Iron(III) clusters bound to horse spleen apoferritin: an X-ray absorption and Moessbauer spectroscopy study that shows that iron nuclei can form on the protein". United States. https://doi.org/10.1021/bi00376a023.
@article{osti_6521688,
title = {Iron(III) clusters bound to horse spleen apoferritin: an X-ray absorption and Moessbauer spectroscopy study that shows that iron nuclei can form on the protein},
author = {Yang, C and Meagher, A and Huynh, B H and Sayers, D E and Theil, E C},
abstractNote = {Ferritin is a complex of a hollow, spherical protein and a hydrous, ferric oxide core of less than or equal to4500 iron atoms inside the apoprotein coat; the apoprotein has multiple binding sites for monoatomic metal ions, e.g., Fe(II), V(IV), Tb(III), that may be important in the initiation of iron core formation. In an earlier study the authors observed that the oxidation of Fe(II) vacated some, but not all, of the metal-binding sites, suggesting migration of some Fe during oxidation, possibly to form nucleation clusters; some Fe(III) remained bound to the protein. Preliminary extended X-ray absorbance fine structure (EXAFS) analysis of the same Fe(III)-apoferritin complex showed an environment distinct from ferritin cores, but the data did not allow a test of the Fe cluster hypothesis. In this paper, with improved EXAFS data and with Moessbauer data on the same complex formed with /sup 57/Fe, they clearly show that the Fe(III) in the distinctive environment is polynuclear. Moreover, the arrangement of atoms is such that Fe(III) atoms appear to have both carboxylate-like ligands, presumably from apoferritin, and oxo bridges to the other iron atoms. Thus the protein provides sites not only for initiation but also for nucleation of the iron core. Sites commodious enough and with sufficient conserved carboxylate ligands to accommodate such a nucleus occur inside the protein coat at the subunit dimer interfaces. Such Fe(III)-apoferritin nucleation complexes can be used to study the properties of the several members of the apoferritin family.},
doi = {10.1021/bi00376a023},
url = {https://www.osti.gov/biblio/6521688}, journal = {Biochemistry; (United States)},
number = ,
volume = 26:2,
place = {United States},
year = {Tue Jan 27 00:00:00 EST 1987},
month = {Tue Jan 27 00:00:00 EST 1987}
}