scholarly journals Incorporation and release of inorganic phosphate in horse spleen ferritin

1978 ◽  
Vol 171 (2) ◽  
pp. 313-320 ◽  
Author(s):  
A Trefry ◽  
P M Harrison
Keyword(s):  
Inorganic Phosphate ◽  
Iron Core ◽  
Ferritin Iron ◽  
Horse Spleen Ferritin

When ferritin is reconstituted from Fe and apoferritin in vitro in the presence of Pi, the product obtained differs both from native ferritin and from ferritin reconstituted in the absence of Pi. When the latter is incubated with Pi the product resembles native ferritin with respect both to the pattern of Pi incorporated per molecule or per Fe atom and to the ease of release of this Pi relative to Fe release. It is concluded that much of the Pi of native ferritin is adsorbed on surfaces of ferritin iron-core crystallites. The results also suggest that Pi is not present at the intracellular site of Fe incorporation into ferritin, but is added after Fe.

THE FORMATION, STRUCTURE AND DISSOLUTION OF THE FERRITIN IRON CORE STUDIED BY X-RAY ABSORPTION SPECTROSCOPY

1986 ◽  
Vol 47 (C8) ◽  
pp. C8-1155-C8-1157
Author(s):  
E. C. THEIL ◽  
D. E. SAYERS ◽  
C. Y. YANG ◽  
A. FONTAINE ◽  
E. DARTYGE
Keyword(s):  
Absorption Spectroscopy ◽  
Iron Core ◽  
X Ray ◽  
Ferritin Iron ◽  
X Ray Absorption

scholarly journals Ferroxidase activity of ferritin: effects of pH, buffer and Fe(II) and Fe(III) concentrations on Fe(II) autoxidation and ferroxidation

1999 ◽  
Vol 338 (3) ◽  
pp. 615-618 ◽  
Author(s):  
Xiaoke YANG ◽  
N. Dennis CHASTEEN
Keyword(s):  
Ph Control ◽  
Alternative Mechanism ◽  
Experimental Conditions ◽  
Iron Storage ◽  
Ferroxidase Activity ◽  
Effects Of Ph ◽  
Ph Stat ◽  
Ph Buffer ◽  
Horse Spleen Ferritin

It is widely accepted that iron deposition in the iron storage protein ferritin in vitro involves Fe(II) oxidation, and that ferritin facilitates this oxidation at a ferroxidase site on the protein. However, these views have recently been questioned, with the protein ferroxidase activity instead being attributed to autoxidation from the buffer alone. Ligand exchange between another protein with ferroxidase activity and ferritin has been proposed as an alternative mechanism for iron incorporation into ferritin. In the present work, a pH stat apparatus is used to eliminate the influence of buffers on iron(II) oxidation. Here we show that the recent experiments questioning the ferroxidase activity of ferritin were flawed by inadequate pH control, that buffers actually retard rather than facilitate iron(II) oxidation, and that horse spleen ferritin has ferroxidase activity when measured under proper experimental conditions. Furthermore, high pH (7.0), a high Fe(II) concentration and the presence of Fe(III) all favour Fe(II) autoxidation in the presence or absence of ferritin.

scholarly journals Reductive Mobilization of Iron from Intact Ferritin: Mechanisms and Physiological Implication

2018 ◽  
Vol 11 (4) ◽  
pp. 120 ◽  
Author(s):  
Fadi Bou-Abdallah ◽  
John Paliakkara ◽  
Galina Melman ◽  
Artem Melman
Keyword(s):  
Protein Structures ◽  
Reducing Agents ◽  
Iron Core ◽  
Ferrous Ions ◽  
Major Pathway ◽  
Iron Mobilization ◽  
Iron Mineral ◽  
Mineral Core

Ferritins are highly conserved supramolecular protein nanostructures composed of two different subunit types, H (heavy) and L (light). The two subunits co-assemble into a 24-subunit heteropolymer, with tissue specific distributions, to form shell-like protein structures within which thousands of iron atoms are stored as a soluble inorganic ferric iron core. In-vitro (or in cell free systems), the mechanisms of iron(II) oxidation and formation of the mineral core have been extensively investigated, although it is still unclear how iron is loaded into the protein in-vivo. In contrast, there is a wide spread belief that the major pathway of iron mobilization from ferritin involves a lysosomal proteolytic degradation of ferritin, and the dissolution of the iron mineral core. However, it is still unclear whether other auxiliary iron mobilization mechanisms, involving physiological reducing agents and/or cellular reductases, contribute to the release of iron from ferritin. In vitro iron mobilization from ferritin can be achieved using different reducing agents, capable of easily reducing the ferritin iron core, to produce soluble ferrous ions that are subsequently chelated by strong iron(II)-chelating agents. Here, we review our current understanding of iron mobilization from ferritin by various reducing agents, and report on recent results from our laboratory, in support of a mechanism that involves a one-electron transfer through the protein shell to the iron mineral core. The physiological significance of the iron reductive mobilization from ferritin by the non-enzymatic FMN/NAD(P)H system is also discussed.

scholarly journals Characterization of Iron Core–Gold Shell Nanoparticles for Anti-Cancer Treatments: Chemical and Structural Transformations During Storage and Use

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2572 ◽  
Author(s):  
Ya-Na Wu ◽  
Dar-Bin Shieh ◽  
Li-Xing Yang ◽  
Hwo-Shuenn Sheu ◽  
Rongkun Thordarson ◽  
...  
Keyword(s):  
Au Nanoparticles ◽  
Iron Core ◽  
Cancer Treatments ◽  
Shell Nanoparticles ◽  
X Ray ◽  
Anti Cancer ◽  
One Year ◽  
Means Of Transmission

Finding a cancer-selective drug that avoids damaging healthy cells and organs is a holy grail in medical research. In our previous studies, gold-coated iron (Fe@Au) nanoparticles showed cancer selective anti-cancer properties in vitro and in vivo but were found to gradually lose that activity with storage or "ageing.” To determine the reasons for this diminished anti-cancer activity, we examined Fe@Au nanoparticles at different preparation and storage stages by means of transmission electron microscopy combined with and energy-dispersive X-ray spectroscopy, along with X-ray diffraction analysis and cell viability tests. We found that dried and reconstituted Fe@Au nanoparticles, or Fe@Au nanoparticles within cells, decompose into irregular fragments of γ-F2O3 and agglomerated gold clumps. These changes cause the loss of the particles’ anti-cancer effects. However, we identified that the anti-cancer properties of Fe@Au nanoparticles can be well preserved under argon or, better still, liquid nitrogen storage for six months and at least one year, respectively.

scholarly journals In Vitro Characterization of Magnetic Resonance Imaging Contrast Agents for Molecular Imaging.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3944-3944
Author(s):  
Zhi Yu ◽  
Michael Grafe ◽  
Heike Meyborg ◽  
Eckart Fleck ◽  
Yangqiu Li
Keyword(s):  
Endothelial Cells ◽  
Molecular Imaging ◽  
Cellular Uptake ◽  
Umbilical Vein ◽  
Biological Properties ◽  
Blue Staining ◽  
Iron Core ◽  
Coated Particles ◽  
Coated Particle

Abstract The aim of this work was to evaluate the biological properties of one citrate-coated and two different dextran-coated paramagnetic particles with comparable size (iron core 4–10 nm). Endothelial cells from humans and mice as well as human macrophages were incubated for different time intervals with different particle suspensions. The cellular uptake was semi-quantitatively measured using the Prussian blue staining and, in addition, by cellular iron content. Furthermore the effect of known inhibitors of endocytosis was evaluated. In addition, it was evaluated whether linking of monoclonal antibodies to dextran-coated particles can make them bind specifically to certain cell surface structures. The results showed that the bEnd.3 cell line, human umbilical vein endothelial cells (HUVECs) and THP-1/macrophage cell lines internalize paramagnetic particles. The ranking of cellular uptake was: VSOP > CMD-coated particles >> CLIO. The carboxydextran-coated SPIO uptake by endothelial cells is reduced by colchicine (50%). Conversely, cytochalasin B down-regulates the endocytosis of citrate-coated particle. Our data imply that the major mechanism of uptake would be pinocytosis for the VSOP and phagocytosis for the carboxydextran-coated particle CMD. The different surface coating can influence not only the quantity of the internalization, but also the pathway of internalization. CLIO linked to CD40 antibodies or to CD62E antibodies bound significantly better than IgG-linked CLIO. This was true especially for the anti-CD40-CLIO constructs where fluorescence increased two fold. Comparable results were observed with anti-CD62E-CLIO constructs; however, increase in fluorescence was higher than with CD40 binding; it increased on 3.9-fold (median) and 4.5-fold (mean). In conclusions, the binding of antibody-conjugated CLIO to the antigen-expressing cells was specific, with an affinity similar to that of the free antibody. Thus, it seems feasible to use antibody linked SPIOs for molecular imaging.

scholarly journals STUDIES OF PHOSPHORUS METABOLISM IN MAN: II. A STUDY OF THE PERMEABILITY OF THE HUMAN ERYTHROCYTE TO INORGANIC PHOSPHATE IN VITRO BY THE USE OF RADIOACTIVE PHOSPHATE (P32)

Blood ◽  
1948 ◽  
Vol 3 (12) ◽  
pp. 1472-1477 ◽  
Author(s):  
F. H. L. TAYLOR ◽  
S. M. LEVENSON ◽  
M. A. ADAMS ◽  
MARY KENDRICK
Keyword(s):  
Human Erythrocyte ◽  
Inorganic Phosphate ◽  
Sodium Phosphate ◽  
Specific Activity ◽  
Soluble Fraction ◽  
High Specific Activity ◽  
Phosphorus Metabolism ◽  
Phosphate Exchange ◽  
Inorganic Fraction

Abstract 1. Phosphate exchange in red cells and plasma was studied in vitro using P32 in the form of sodium phosphate as a tracer. 2. No phosphate was added other than the isotopic preparation which was of high specific activity. 3. Inorganic phosphate exchanged freely between the plasma and the erythrocytes at 37.5 C. in a period of four hours. Minimal transfer occurred at 7 C. 4. Most of the added P32 which passed into the erythrocytes during this time remained in the inorganic fraction, less than 15 per cent being found in the organic acid soluble fraction. 5. The specific activity of the inorganic phosphate of the erythrocytes was equal to or greater than that obtaining for the inorganic phosphate of the plasma at the end of the four hour incubation period at 37.5 C.

scholarly journals Inorganic Phosphate Solubilization by a Novel Isolated Bacterial Strain Enterobacter sp. ITCB-09 and Its Application Potential as Biofertilizer

Agriculture ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 383 ◽  
Author(s):  
Gustavo Enrique Mendoza-Arroyo ◽  
Manuel Jesús Chan-Bacab ◽  
Ruth Noemi Aguila-Ramírez ◽  
Benjamín Otto Ortega-Morales ◽  
René Efraín Canché Solís ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Inorganic Phosphate ◽  
Extracellular Polymeric Substances ◽  
Phosphate Solubilization ◽  
Rrna Gene ◽  
Bacterial Strains ◽  
Habanero Pepper ◽  
Phosphate Solubilizing

The excessive use of fertilizers in agriculture is mainly due to the recognized plant requirements for soluble phosphorus. This problem has limited the implementation of sustainable agriculture. A viable alternative is to use phosphate solubilizing soil microorganisms. This work aimed to isolate inorganic phosphorus-solubilizing bacteria from the soils of agroecosystems, to select and identify, based on sequencing and phylogenetic analysis of the 16S rRNA gene, the bacterium with the highest capacity for in vitro solubilization of inorganic phosphate. Additionally, we aimed to determine its primary phosphate solubilizing mechanisms and to evaluate its effect on Habanero pepper seedlings growth. A total of 21 bacterial strains were isolated by their activity on Pikovskaya agar. Of these, strain ITCB-09 exhibited the highest ability to solubilize inorganic phosphate (865.98 µg/mL) through the production of organic acids. This strain produced extracellular polymeric substances and siderophores that have ecological implications for phosphate solubilization. 16S rRNA gene sequence analysis revealed that strain ITCB-09 belongs to the genus Enterobacter. Enterobacter sp. ITCB-09, especially when immobilized in beads, had a positive effect on Capsicum chinense Jacq. seedling growth, indicating its potential as a biofertilizer.

scholarly journals Multiresponsive Hybrid Microparticles for Stimuli-Responsive Delivery of Bioactive Compounds

2020 ◽  
Vol 10 (12) ◽  
pp. 4324 ◽  
Author(s):  
Sergei S. Vlasov ◽  
Pavel S. Postnikov ◽  
Mikhail V. Belousov ◽  
Sergei V. Krivoshchekov ◽  
Mekhman S. Yusubov ◽  
...  
Keyword(s):  
Cell Viability ◽  
Spherical Shape ◽  
In Vitro Cytotoxicity ◽  
Poly Lactic Acid ◽  
Iron Core ◽  
Stimuli Responsive ◽  
Ultrasonic Fields ◽  
Burst Intensity ◽  
Free Doxorubicin

Hybrid microparticles based on an iron core and an amphiphilic polymeric shell have been prepared to respond simultaneously to magnetic and ultrasonic fields and variation in the surrounding pH to trigger and modulate the delivery of doxorubicin. The microparticles have been developed in four steps: (i) synthesis of the iron core; (ii) surface modification of the core; (iii) conjugation with the amphiphilic poly(lactic acid)-grafted chitosan; and (iv) doxorubicin loading. The particles demonstrate spherical shape, a size in the range of 1–3 µm and surface charge that is tuneable by changing the pH of the environment. The microparticles demonstrate good stability in simulated physiological solutions and are able to hold up to 400 µg of doxorubicin per mg of dried particles. The response to ultrasound and the changes in the shell structure during exposure to different pH levels allows the control of the burst intensity and release rate of the payload. Additionally, the magnetic response of the iron core is preserved despite the polymer coat. In vitro cytotoxicity tests performed on fibroblast NIH/3T3 demonstrate a reduction in the cell viability after administration of doxorubicin-loaded microparticles compared to the administration of free doxorubicin. The application of ultrasound causes a burst in the release of the doxorubicin from the carrier, causing a decrease in cell viability. The microparticles demonstrate in vitro cytocompatibility and hemocompatibility at concentrations of up to 50 and 60 µg/mL, respectively.

In vitro re-mineralization of demineralized bone matrix in human serum

2006 ◽  
Vol 44 (1) ◽  
Author(s):  
Metin Manouchehr Eskandari ◽  
Hatice Gulcin Eskandari ◽  
Melih Aktas ◽  
Ugur Atik
Keyword(s):  
Human Serum ◽  
Serum Calcium ◽  
Inorganic Phosphate ◽  
Mineral Content ◽  
Demineralized Bone Matrix ◽  
Bone Matrix ◽  
Calcium Content ◽  
Study Groups ◽  
Phosphate Content

AbstractThe aim of this study was to develop an in vitro re-mineralization model in human serum. For this purpose a commercially produced demineralized human bone matrix (DBM) was incubated in samples of human serum pools obtained from two physiologically different groups. The first group consisted of young males and the second of older females. After incubation periods of 4 and 7days at 37°C, changes in the levels of calcium and inorganic phosphate content of the serum and DBM samples were measured. The results of the study showed that the change in mineral content of serum and DBM samples in both study groups was statistically significant. The decrease in serum calcium content and increase in DBM inorganic phosphate content were significant in the young group for longer incubation times. In the older group, both serum calcium and inorganic phosphate decreased and DBM mineral content increased for the same incubation time. When the two physiological groups were compared, statistically significant differences were identified for changes in mineral levels in both serum and the DBM samples. These data indicate that the mineral content of human serum decreases and that of DBM increases when these two materials are incubated together. These changes provide evidence for the re-mineralization of DBM. The model described here could also detect a difference in re-mineralization capability between two different groups of human sera.

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