Structure of the iron-containing core in ferritin by the extended x-ray absorption fine structure technique

Heald, S. M.; Stern, Edward A.; Bunker, Bruce A.; Holt, E. M.; Holt, Sarah

doi:10.1021/ja00495a012

Cited by 79 publications

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“…The absorption edge spectrum presented here, although of low resolution, suggests a similar tetrahedral iron content to that of maghemite (37.5%), and the model, derived from XRD intensities, has 36% tetrahedral iron. The EXAFS results of Heald et al (1979) for the insoluble ferric hydroxide polymer suggest a coordination number for Fe 3 + of 5.4. A structure having 35% tetrahedral and 65% octahedral iron would have an average coordination number of 5.3.…”

Section: Discussionmentioning

confidence: 95%

“…On the other hand, several published DTA studies on pure synthetic ferrihydrites have yielded single exotherms which are not consistent with our results, probably because the ferrihydrites were synthesized under different conditions. The synthesis results of Heald et al (1979) show that two different polymers are readily produced during the hydrolysis of ferric salts, and Goncharov et al (1978) concluded that the structure of the precipitate is determined by the structure of the polynuclear seeds, which in turn depend on the procedure used. Therefore, the crystal structure of ferrihydrite may be dependent on the mode of formation, and each study may be related to a somewhat different proportion of Fe in tetrahedral and octahedral coordination.…”

Section: Discussionmentioning

confidence: 99%

“…The absorption from the tetrahedrally coordinated iron decreased with time (12 weeks), whereas that from the octahedral complex was not time dependent. Heald et al (1979) used the extended X-ray absorption fine structure (EXAFS) technique to assess the coordination of iron in ferritin and in hydrolyzed Fe 3+ polymers. They distinguished two varieties of polymer: a soluble, spherical polymer (type A) identical with that described by Spiro et al (1966) and an insoluble polymer (type B).…”

Section: Review Of Previous Workmentioning

confidence: 99%

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New Data and a Revised Structural Model for Ferrihydrite

Eggleton

Fitzpatrick

1988

Clays and clay miner.

293

208

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Abstract--Synthetic 2-line and 6-line ferrihydrite samples prepared from ferric nitrate solutions have the bulk compositions Fe4(O,OH,H20)12 and Fe4.6(O,OH,H20)lZ, respectively. The composition depends on crystal size, which averages 20/~ for 2-line and 35/k for 6-line ferrihydrite. X-ray absorption edge spectra indicate the presence of tetrahedral Fe 3+, a conclusion supported by heating experiments which show the development of maghemite after heating to 300~ in the presence of N2, followed by the formation of hematite at higher temperatures. These two reactions are recorded on differential thermal analysis traces by exotherms at 350 ~ and 450~ Transmission electron microscopy shows that 2-line ferrihydrite has no Z-axis regularity but does show hexagonal 2.54-/~ lattice fringes. Six-line ferrihydrite forms faceted crystals having 9.4-/~ c-parameter only detectable in dark field. In bright field, 2.54-/~ lattice fringes indicate greater atomic regularity than in 2-line ferrihydrite. Analysis of the X-ray powder diffraction pattern of 6-line ferrihydrite suggests a structure based on double-hexagonal close-packed oxygens, containing 36% Fe in tetrahedral sites. Selective chemical dissolution, surface area measurements, and magnetic susceptibility are consistent with the recorded properties of ferrihydrite.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Review Of Previous Workmentioning

confidence: 99%

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New Data and a Revised Structural Model for Ferrihydrite

Eggleton

Fitzpatrick

1988

Clays and clay miner.

293

208

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“…3. It shows strong oscillations at the short-wavelength side of the absorption edge, which have been analyzed by Heald, Stern, Bunker, Holt & Holt (1979). In order to establish the consistence of p with R, we make use of As this study is aiming at the dispersion off' and f" near the absorption edge only, (17) can be simplified,…”

Section: Small-angle Scattering Of Horse-spleen Ferritinmentioning

confidence: 99%

Anomalous dispersion of small-angle scattering of horse-spleen ferritin at the ironKabsorption edge

Stuhrmann¹

1980

Acta Cryst Sect A

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The primary extinction approach considered can be used for the analysis of the diffraction data, measured on polycrystals, if the dislocation density in a crystal grain satisfies the applicability condition of the mosaic model.We would like to thank the referees for their helpful suggestions for improvements to the paper. Abstract Small-angle scattering experiments of horse-spleen ferritin solutions have been performed at various wavelengths near the K absorption edge of iron, using synchrotron radiation from the storage ring DORIS. The anomalous dispersion of the atomic form factor f as described by f' and tf" has been monitored by the 0567-7394/80/060996-06501.00dependence of the radius of gyration R and the absorption coefficient p respectively. There is a 4% increase of R at the absorption edge. The relative full half width of this peak of 0.0016 corresponding to 1 1 eV of the energy scale reflects the drastic variation off' by 7 electrons. The predictable relation between R and has been verified by the Kramers-Kronig relation. As small-angle scattering is primarily influenced byf', best © 1980 International Union of Crystallography H. B. STUHRMANN 997 advantage from anomalous dispersion in small-angle scattering can be taken by measurements very near the absorption edges.

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“…The Fe 3 O 7+ units has been proposed as the smallest building block of the ferritin core 7,8 , since it is know that hemerythrin, methane monooxygenase and ribonucleotide reductase have diiron active sites with µ-oxo and µ-carboxylate bridges 9,10 . The ferric core of ferritine, exhibits the phenomenon of super paramagnetism 11 .…”

Section: Introductionmentioning

confidence: 99%

Magnetic Behavior and Antibacterial Activity of Iron (Iii) Complexes

Cortés-Cortés

Atria

Contreras

et al. 2008

J. Chil. Chem. Soc.

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The preparation, magnetic characterization and antimicrobial properties of the complexes [Fe 3 O) (2), where MeImid is 2-methyl-imidazolium and BPA is 2,2´-bipyridine, are described.The variable temperature susceptibilities of these complexes were investigated in the temperature range 2-300K. The data have been modeled on the assumption of "butterfly" arranged for (2) and equilateral triangle of ferric ions for (1).The antimicrobial activities of these complexes have been screened in vitro against different bacterial strains. The complexes (1) and (2) display activity over Gram negative bacteria and these compounds not present activity over Gram positive strains. These complexes have bacteriostatic effect over bacterial target. The toxicity analyses of iron complexes showed these have cytotoxicity effect to values around the MIC on human cell.

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Structure of the iron-containing core in ferritin by the extended x-ray absorption fine structure technique

Cited by 79 publications

References 0 publications

New Data and a Revised Structural Model for Ferrihydrite

New Data and a Revised Structural Model for Ferrihydrite

Anomalous dispersion of small-angle scattering of horse-spleen ferritin at the ironKabsorption edge

Magnetic Behavior and Antibacterial Activity of Iron (Iii) Complexes

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