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Title: The Ferritin Protein Nanocage and Biomineral, from Single Fe Atoms to FeO Nanoparticles: Starting with EXAFS

Abstract

Ferritins are protein nanocages that use iron and oxygen chemistry to concentrate iron and trap dioxygen or hydrogen peroxide in biominerals of hydrated ferric oxides, 5-8 nm in diameter, inside the cages. The proteins are found in nature from archea to humans. Protein catalytic sites are embedded in the protein cage and initiate mineralization by oxido-reduction of ferrous ions and dioxygen or hydrogen peroxide to couple two iron ions through a peroxo bridge, followed by decay to diferric oxo/hydroxyl mineral precursors; ferritin protein subdomains that fold/unfold independently of the protein cage control recovery of ferrous ions from the mineral. Early EXAFS (1978) was extremely useful in defining the ferritin mineral. More recent use of rapid freeze quench (RFQ) EXAFS spectroscopies, coupled with RFQ Moessbauer, Resonance Raman and rapid mixing UV-vis spectroscopy, have identified and characterized unusual ferritin protein catalytic intermediates and mineral precursors. EXAFS spectroscopy can play an important role in the future understanding of protein catalysis in metalloproteins such as ferritin, ribonucleotide reductase and methane monooxygenases. Needed are instrumentation improvements that will provide rapid-scan fluorescence spectra with high signal/noise ratios.

Authors:
 [1];  [2]
  1. Children's Hospital Oakland Research Institute (CHORI), 5700 Martin Luther King Jr. Way, Oakland, CA 94609 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
21054581
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 882; Journal Issue: 1; Conference: XAFS13: 13. international conference on X-ray absorption fine structure, Stanford, CA (United States), 9-14 Jul 2006; Other Information: DOI: 10.1063/1.2644422; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION SPECTROSCOPY; ATOMS; CATALYSIS; FERRITIN; FINE STRUCTURE; FLUORESCENCE SPECTROSCOPY; HYDROGEN PEROXIDE; HYDROXIDES; IRON; IRON IONS; IRON OXIDES; MINERALIZATION; MINERALS; NANOSTRUCTURES; OXIDATION; OXYGEN; REDUCTION; SIGNAL-TO-NOISE RATIO; TRAPS; X-RAY SPECTROSCOPY

Citation Formats

Theil, Elizabeth C., and Department of Nutritional Science and Toxicology, University of California, Berkeley, CA 94720. The Ferritin Protein Nanocage and Biomineral, from Single Fe Atoms to FeO Nanoparticles: Starting with EXAFS. United States: N. p., 2007. Web. doi:10.1063/1.2644422.
Theil, Elizabeth C., & Department of Nutritional Science and Toxicology, University of California, Berkeley, CA 94720. The Ferritin Protein Nanocage and Biomineral, from Single Fe Atoms to FeO Nanoparticles: Starting with EXAFS. United States. doi:10.1063/1.2644422.
Theil, Elizabeth C., and Department of Nutritional Science and Toxicology, University of California, Berkeley, CA 94720. Fri . "The Ferritin Protein Nanocage and Biomineral, from Single Fe Atoms to FeO Nanoparticles: Starting with EXAFS". United States. doi:10.1063/1.2644422.
@article{osti_21054581,
title = {The Ferritin Protein Nanocage and Biomineral, from Single Fe Atoms to FeO Nanoparticles: Starting with EXAFS},
author = {Theil, Elizabeth C. and Department of Nutritional Science and Toxicology, University of California, Berkeley, CA 94720},
abstractNote = {Ferritins are protein nanocages that use iron and oxygen chemistry to concentrate iron and trap dioxygen or hydrogen peroxide in biominerals of hydrated ferric oxides, 5-8 nm in diameter, inside the cages. The proteins are found in nature from archea to humans. Protein catalytic sites are embedded in the protein cage and initiate mineralization by oxido-reduction of ferrous ions and dioxygen or hydrogen peroxide to couple two iron ions through a peroxo bridge, followed by decay to diferric oxo/hydroxyl mineral precursors; ferritin protein subdomains that fold/unfold independently of the protein cage control recovery of ferrous ions from the mineral. Early EXAFS (1978) was extremely useful in defining the ferritin mineral. More recent use of rapid freeze quench (RFQ) EXAFS spectroscopies, coupled with RFQ Moessbauer, Resonance Raman and rapid mixing UV-vis spectroscopy, have identified and characterized unusual ferritin protein catalytic intermediates and mineral precursors. EXAFS spectroscopy can play an important role in the future understanding of protein catalysis in metalloproteins such as ferritin, ribonucleotide reductase and methane monooxygenases. Needed are instrumentation improvements that will provide rapid-scan fluorescence spectra with high signal/noise ratios.},
doi = {10.1063/1.2644422},
journal = {AIP Conference Proceedings},
number = 1,
volume = 882,
place = {United States},
year = {Fri Feb 02 00:00:00 EST 2007},
month = {Fri Feb 02 00:00:00 EST 2007}
}
  • The interaction of Fe0 atoms and clusters with CCl4 multilayers was investigated using a novel "atom dropping" method at 30 K over a FeO(111) thin film. Temperature programmed desorption experiments over a range of Fe0 and CCl4 coverages demonstrate a rich surface chemistry with several reaction products (C2Cl4, C2Cl6, OCCl2, CO, FeCl2, FeCl3) observed. X-ray photoelectron spectroscopy data show that the initial reactive interaction occurs spontaneously at 30 K, with the experimentally observed reaction products formed at higher temperature, in agreement with the results of theoretical calculations. The formation of OCCl2 and CO is concluded to occur through abstraction ofmore » O atoms from the generally inert FeO(111) substrate. The buffer layer assisted growth technique is used to show that the reactivity, and interestingly the reaction products, is determined by the size of Fe0 nanoparticles which interact with CCl4.« less
  • The iron core of proteins in the ferritin family displays structural variations that includes phosphate content was well as the number and the degree of ordering of the iron atoms. Earlier studies had shown that ferritin iron cores naturally high in phosphate, e.g., Azotobacter vinelandii (AV) ferritin had decreased long-range order. Here, the influence of phosphate on the local structure around iron in ferritin cores is reported, comparing the EXAFS of AV ferritin, reconstituted ferritin and native horse spleen ferritin. In contrast, when the phosphate content was high in AV ferritin and horse spleen ferritin reconstituted with phosphate, the averagemore » iron atom had five to six phosphorus neighbors at 3.17 {angstrom}. Moreover, the number of detectable iron neighbors was lower when phosphate was high or present during reconstitution and the interatomic distance was longer indicating that some phosphate bridges neighboring iron atoms. However, the decrease in the number of detectable iron-iron neighbors compared to HSF and the higher number of Fe-P interactions relative to Fe-Fe interactions suggest that some phosphate ligands were chain termini, or blocked crystal growth, and/or introduced defects which contributed both to the long-range disorder and to altered redox properties previously observed in AV ferritin.« less
  • Bi{sub 0.9}La{sub 0.1}FeO{sub 3} (BLFO) and Bi{sub 0.9}La{sub 0.1}Fe{sub 0.99}Zn{sub 0.01}O{sub 3} (BLFZO) nanoparticles were prepared via a sol-gel method. The oxygen vacancies and holes increase with Zn doping analyzed through X-ray photoelectron spectroscopy, which could contribute to the increase of leakage current density. However, with the increase of the defects (oxygen vacancies and holes), the band gap of BLFZO also is increased. To explain the abnormal phenomenon, the bandwidth of occupied and unoccupied bands was analyzed based on the structural symmetry driven by the Fe-O-Fe bond angle and Fe-O bond anisotropy.
  • No abstract prepared.