Nanophase Iron Phosphate, Iron Arsenate, Iron Vanadate, and Iron Molybdate Minerals Synthesized within the Protein Cage of Ferritin

Polanams, Jup; Ray, and Alisha D.; Watt, Richard K.

doi:10.1021/ic048819r

Cited by 77 publications

(76 citation statements)

References 51 publications

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“…The addition of 1.0, 2.5, 5, and 10 mM phosphate to this reaction caused an increase in the initial rate of apo transferrin loading, indicating that the phosphate stimulates the rate of Fe 2? oxidation at the H ferritin ferroxidase center as previously reported (Orino et al 2002;Aitken-Rogers et al 2004;Cheng and Chasteen 1991;Polanams et al 2005). However, above 2.5 mM phosphate, the final absorbance begins to decrease, indicating that at these higher phosphate concentrations, the formation of the Fe(III)-phosphate complex begins to compete with H ferritin for the added Fe 2?…”

Section: Recombinant H and L Ferritinssupporting

confidence: 75%

“…As indicated above, CKD patients have elevated serum ferritin concentrations suggesting a possible role for ferritin as an NTBI binding protein. Also, consistent with this hypothesis are reports that ferritin has increased rates of iron loading in the presence of phosphate (Aitken-Rogers et al 2004;Orino et al 2002;Cheng and Chasteen 1991;Polanams et al 2005;de Silva et al 1993).…”

Section: Introductionsupporting

confidence: 60%

“…Ferritin loaded with iron shows a peak at 280 nm as well as a shoulder trailing into the visible region between 300 and 450 nm, characteristic of iron inside ferritin. The ferritin sample loaded with both iron and phosphate has a similar spectrum as ferritin and iron only, but has a lower absorbance than the ferritin sample from 325 to 450 nm, suggesting that a different mineral with a different extinction coefficient has formed inside ferritin (Polanams et al 2005). The Fe(III)-phosphate complex that forms independent of ferritin has a peak near 280 nm that trails off into the visible in a similar fashion as ferritin containing iron, but this spectrum has much less absorbance.…”

Section: Fe(iii)-pi Complexmentioning

confidence: 99%

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The ferroxidase center is essential for ferritin iron loading in the presence of phosphate and minimizes side reactions that form Fe(III)-phosphate colloids

2011

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Ferritin iron loading was studied in the presence of physiological serum phosphate concentrations (1 mM), elevated serum concentrations (2-5 mM), and intracellular phosphate concentrations (10 mM). Experiments compared iron loading into homopolymers of H and L ferritin with horse spleen ferritin. Prior to studying the reactions with ferritin, a series of control reactions were performed to study the solution chemistry of Fe(2+) and phosphate. In the absence of ferritin, phosphate catalyzed Fe(2+) oxidation and formed soluble polymeric Fe(III)-phosphate complexes. The Fe(III)-phosphate complexes were characterized by electron microscopy and atomic force microscopy, which revealed spherical nanoparticles with diameters of 10-20 nm. The soluble Fe(III)-phosphate complexes also formed as competing reactions during iron loading into ferritin. Elemental analysis on ferritin samples separated from the Fe(III)-phosphate complexes showed that as the phosphate concentration increased, the iron loading into horse ferritin decreased. The composition of the mineral that does form inside horse ferritin has a higher iron/phosphate ratio (~1:1) than ferritin purified from tissue (~10:1). Phosphate significantly inhibited iron loading into L ferritin, due to the lack of the ferroxidase center in this homopolymer. Spectrophotometric assays of iron loading into H ferritin showed identical iron loading curves in the presence of phosphate, indicating that the ferroxidase center of H ferritin efficiently competes with phosphate for the binding and oxidation of Fe(2+). Additional studies demonstrated that H ferritin ferroxidase activity could be used to oxidize Fe(2+) and facilitate the transfer of the Fe(3+) into apo transferrin in the presence of phosphate.

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Section: Recombinant H and L Ferritinssupporting

confidence: 75%

Section: Introductionsupporting

confidence: 60%

Section: Fe(iii)-pi Complexmentioning

confidence: 99%

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The ferroxidase center is essential for ferritin iron loading in the presence of phosphate and minimizes side reactions that form Fe(III)-phosphate colloids

2011

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“…In vivo the phosphate contents of ferritin iron cores appear to be in dynamic equilibrium with cell phosphate (Ford et al, 1984) and it has long been suggested that phosphate plays a role in iron home-ostasis (Powell, 1998). This assumption has recently been supported by the fact that phosphate can stimulate the rate of iron uptake by providing binding sites on the mineral surface for incoming iron atoms and as such may play a role in the oxidation of Fe 2+ on the mineral surface (Polanams et al, 2005).…”

Section: +mentioning

confidence: 96%

Ferritin and ferritin isoforms I: Structure–function relationships, synthesis, degradation and secretion

Koorts

Viljoen

2007

Archives of Physiology and Biochemistry

134

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Ferritin is the intracellular protein responsible for the sequestration, storage and release of iron. Ferritin can accumulate up to 4500 iron atoms as a ferrihydrite mineral in a protein shell and releases these iron atoms when there is an increase in the cell's need for bioavailable iron. The ferritin protein shell consists of 24 protein subunits of two types, the H-subunit and the L-subunit. These ferritin subunits perform different functions in the mineralization process of iron. The ferritin protein shell can exist as various combinations of these two subunit types, giving rise to heteropolymers or isoferritins. Isoferritins are functionally distinct and characteristic populations of isoferritins are found depending on the type of cell, the proliferation status of the cell and the presence of disease. The synthesis of ferritin is regulated both transcriptionally and translationally. Translation of ferritin subunit mRNA is increased or decreased, depending on the labile iron pool and is controlled by an ironresponsive element present in the 5'-untranslated region of the ferritin subunit mRNA. The transcription of the genes for the ferritin subunits is controlled by hormones and cytokines, which can result in a change in the pool of translatable mRNA. The levels of intracellular ferritin are determined by the balance between synthesis and degradation. Degradation of ferritin in the cytosol results in complete release of iron, while degradation in secondary lysosomes results in the formation of haemosiderin and protection against iron toxicity. The majority of ferritin is found in the cytosol. However, ferritin with slightly different properties can also be found in organelles such as nuclei and mitochondria. Most of the ferritin produced intracellularly is harnessed for the regulation of iron bioavailability; however, some of the ferritin is secreted and internalized by other cells. In addition to the regulation of iron bioavailability ferritin may contribute to the control of myelopoiesis and immunological responses.

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“…A synthesis of ferrimagnetic ferritin (γ-Fe 2 O 3 ) was achieved by a chemical remineralization procedure [7,8] with the assistance of H 2 O 2 oxidant in 3-[(1,1-dimethyl-2-hydroxyethyl)amino]-2-hydroxypropanesulfonic acid(AMPSO) buffer (pH 8.5) at 65 o C under N 2 gas. Biomineralization of other metals (i.e., Co [9,11], Mn [12][13][14], Ni [15], and Pd [16]), semiconductors (CdS) [17], and metal-oxo-anions composites [18] into the ferritin cavity has also been reported. Wong et al demonstrated the magnetic transition from superparamagnetic to ferromagnetic CoPt cored ferritin [19][20].…”

Section: Introductionmentioning

confidence: 99%

Electrochemically controlled reconstitution of immobilized ferritins for bioelectronic applications

Kim

Choi

Lillehei

et al. 2007

Journal of Electroanalytical Chemistry

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Nanophase Iron Phosphate, Iron Arsenate, Iron Vanadate, and Iron Molybdate Minerals Synthesized within the Protein Cage of Ferritin

Cited by 77 publications

References 51 publications

The ferroxidase center is essential for ferritin iron loading in the presence of phosphate and minimizes side reactions that form Fe(III)-phosphate colloids

The ferroxidase center is essential for ferritin iron loading in the presence of phosphate and minimizes side reactions that form Fe(III)-phosphate colloids

Ferritin and ferritin isoforms I: Structure–function relationships, synthesis, degradation and secretion

Electrochemically controlled reconstitution of immobilized ferritins for bioelectronic applications

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