scholarly journals The formation of ferritin from apoferritin. Catalytic action of apoferritin

1973 ◽  
Vol 135 (2) ◽  
pp. 343-348 ◽  
Author(s):  
Ian G. Macara ◽  
Terence G. Hoy ◽  
Pauline M. Harrison
Keyword(s):  
Ferric Oxide ◽  
Ferrous Iron ◽  
Protein Molecule ◽  
Iron Core ◽  
Oxidizing Agent ◽  
Iron Storage ◽  
Oxide Hydrate ◽  
Initial Stage ◽  
Protein Shell ◽  
Iron Storage Protein

The iron-storage protein ferritin consists of a protein shell and has an iron content of up to 4500 iron atoms as a microcrystalline ferric oxide hydrate. A study was made of the uptake of ferrous iron by apoferritin in the presence of an oxidizing agent at very low iron:protein ratios. At ratios of less than about 150 iron atoms per apoferritin molecule hyperbolic progress curves were obtained, whereas at higher ratios the curves became sigmoidal under the conditions used. A computer model, developed previously (Macara et al., 1972), was shown to account for this result. The experimental evidence indicates that apoferritin binds ferrous iron and catalyses the initial stage in the formation of the ferric oxide hydrate inside the protein shell. This stage involves the oxidation of sufficient iron within the protein molecule to form a stable nucleus on which the growth of the microcrystalline iron-core particles can proceed. A possible schematic mechanism for the action of apoferritin is suggested.

Ultrastructural Analysis of the Disruption of Ferritin by Acetone

1977 ◽  
Vol 35 ◽  
pp. 476-477
Author(s):  
William H. Massover
Keyword(s):  
Macromolecular Complex ◽  
Freezing And Thawing ◽  
Subunit Interactions ◽  
Iron Storage ◽  
Protein Subunits ◽  
Chemical Treatments ◽  
Physical Treatments ◽  
Horse Spleen Ferritin ◽  
Protein Shell ◽  
Iron Storage Protein

Ferritin is the major iron-storage protein in mammals (1, 2). The basic architecture of this large macromolecular complex originally was established in the 1954 electron microscope study by Farrant (3). Each ferritin molecule is a hollow sphere formed by the polymerization of 24 protein subunits; the ferric iron is sequestered within the central cavity as one or more crystallites of a unique mineral (1-4). The protein shell resists depolymerization by many harsh chemical treatments; this stability suggests that the subunit- subunit interactions are very strong. A partial disruption of some protein shells has been produced by certain physical treatments, such as freezing and thawing, boiling and cooling, and, drying and rehydrating (5).Acetone has been used to precipitate ferritin from its aqueous solution (6). Dilution of acetone-precipitated ferritin with distilled water appears to result in complete resolubilization. The present study has examined the ultrastructure of horse spleen ferritin (Calbiochem) after this seemingly innocuous treatment.

scholarly journals M?ssbauer Effect In Ferritin

1966 ◽  
Vol 19 (4) ◽  
pp. 573 ◽  
Keyword(s):  
Electron Microscopy ◽  
Storage Protein ◽  
Iron Storage ◽  
Protein Shell ◽  
Iron Storage Protein

By Ferritin, the iron storage protein, is made up of a roughly spherical apo-protein shell enclosing a micelle of composition (FeOOH)s(FeO.OP03H2) (Granick and Hahn 1944; Farrant 1954). Electron microscopy (Farrant 1954; van Bruggen, Wiebenga, and Gruber 1960) showed that the micelle is approximately 55 A in diameter.

scholarly journals Magnetoferritin: Process, Prospects, and Their Biomedical Applications

2019 ◽  
Vol 20 (10) ◽  
pp. 2426 ◽  
Author(s):  
Le Xue ◽  
Dawei Deng ◽  
Jianfei Sun
Keyword(s):  
Catalytic Activity ◽  
Iron Oxide ◽  
Biomedical Applications ◽  
Biomimetic Synthesis ◽  
Iron Core ◽  
Biomimetic Mineralization ◽  
Iron Storage ◽  
Magnetic Nanomaterial ◽  
Good Biocompatibility ◽  
Iron Storage Protein

Ferritin is a spherical iron storage protein composed of 24 subunits and an iron core. Using biomimetic mineralization, magnetic iron oxide can be synthesized in the cavity of ferritin to form magnetoferritin (MFt). MFt, also known as a superparamagnetic protein, is a novel magnetic nanomaterial with good biocompatibility and flexibility for biomedical applications. Recently, it has been demonstrated that MFt had tumor targetability and a peroxidase-like catalytic activity. Thus, MFt, with its many unique properties, provides a powerful platform for tumor diagnosis and therapy. In this review, we discuss the biomimetic synthesis and biomedical applications of MFt.

scholarly journals Defining the roles of the threefold channels in iron uptake, iron oxidation and iron-core formation in ferritin: a study aided by site-directed mutagenesis

1993 ◽  
Vol 296 (3) ◽  
pp. 721-728 ◽  
Author(s):  
A Treffry ◽  
E R Bauminger ◽  
D Hechel ◽  
N W Hodson ◽  
I Nowik ◽  
...  
Keyword(s):  
Iron Uptake ◽  
Iron Oxidation ◽  
Site Directed Mutagenesis ◽  
Iron Core ◽  
Directed Mutagenesis ◽  
Difference Spectroscopy ◽  
Iron Storage ◽  
Ferritin Iron ◽  
Iron Storage Protein

This paper aims to define the role of the threefold intersubunit channels in iron uptake and sequestration processes in the iron-storage protein, ferritin. Iron uptake, measured as loss of availability of Fe(II) to ferrozine (due to oxidation), has been studied in recombinant human H-chain ferritins bearing amino acid substitutions in the threefold channels or ferroxidase centres. Similar measurements with recombinant horse L-chain ferritin are compared. It is concluded that significant Fe(II) oxidation occurs only at the H-chain ferroxidase centres and not in the threefold channels, although this route is used by Fe(II) for entry. Investigations by Mössbauer and u.v.-difference spectroscopy show that part of the iron oxidized by H-chain ferritin returns to the threefold channels as Fe(III). This monomeric Fe(III) can be displaced by addition of Tb(III). Fe(III) also moves into the cavity for formation of the iron-core mineral, ferrihydrite. Iron incorporated into ferrihydrite becomes kinetically inert.

Polygonal profiles of ferritin molecules

1983 ◽  
Vol 41 ◽  
pp. 600-601
Author(s):  
William H. Massover
Keyword(s):  
Axial Ratio ◽  
X Ray Diffraction ◽  
Rhombic Dodecahedron ◽  
Apparent Contradiction ◽  
Iron Storage ◽  
X Ray ◽  
Hexagonal Shape ◽  
Axes Of Symmetry ◽  
Apparent Conflict ◽  
Iron Storage Protein

The molecular structure of the iron-storage protein, ferritin, is becoming known in ever finer detail. The 24 apoferritin subunits (MW ca. 20,000) have a 2:1 axial ratio and are polymerized with 4:3:2 symmetry to form an outer shell surrounding a variable amount of microcrystalline iron, Recent x-ray diffraction results indicate that the projected outline of the native molecule has a quasi-hexagonal shape when viewed down the 3-fold axes of symmetry, and a quasi-square shape when looking down the 4-fold axes. To date, no electron microscope study has reported observing anything other than circular profiles, which would indicate that ferritin is strictly spherical. The apparent conflict between the "hollow sphere" of electron microscopy (E.M.) and the "truncated rhombic dodecahedron" of x-ray diffraction could reflect the poorer effective resolution of E.M. coming from radiation damage, staining, drying, etc. The present study investigates the detailed shape of individual ferritin molecules in order to search for the predicted aspherical profiles and to interpret the nature of this apparent contradiction.

scholarly journals pH-depended protein shell dis- and reassembly of ferritin nanoparticles revealed by atomic force microscopy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Lukas Stühn ◽  
Julia Auernhammer ◽  
Christian Dietz
Keyword(s):  
Atomic Force Microscopy ◽  
Ph Value ◽  
Surrounding Medium ◽  
Real Space ◽  
Iron Storage ◽  
Liquid Environment ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dependent Change ◽  
Protein Shell

AbstractFerritin, a protein that is present in the human body for a controlled iron storage and release, consists of a ferrihydrite core and a protein shell. Apoferritin, the empty shell of ferritin, can be modified to carry tailored properties exploitable for targeted and direct drug delivery. This protein shell has the ability to dis- and reassemble depending on the pH value of the liquid environment and can thus be filled with the desired substance. Here we observed the dis- and reassembly process of the protein shell of ferritin and apoferritin in situ and in real space using atomic force microscopy. Ferritin and apoferritin nanoparticles adsorbed on a mica substrate exhibited a change in their size by varying the pH value of the surrounding medium. Lowering the pH value of the solution led to a decrease in size of the nanoparticles whereas a successive increase of the pH value increased the particle size again. The pH dependent change in size could be related to the dis- and reassembling of the protein shell of ferritin and apoferritin. Supplementary imaging by bimodal magnetic force microscopy of ferritin molecules accomplished in air revealed a polygonal shape of the core and a three-fold symmetry of the protein shell providing valuable information about the substructure of the nanoparticles.

Analysis of Iron in Ferritin, the Iron-Storage Protein: A General Chemistry Experiment

1998 ◽  
Vol 75 (4) ◽  
pp. 437 ◽  
Author(s):  
Maureen J. Donlin ◽  
Regina F. Frey ◽  
Christopher Putnam ◽  
Jody Proctor ◽  
James K. Bashkin
Keyword(s):  
General Chemistry ◽  
Storage Protein ◽  
Protein A ◽  
Iron Storage ◽  
Chemistry Experiment ◽  
Iron Storage Protein

scholarly journals Preparation of platinum nanoparticles using iron(ii) as reductant and photosensitized H2 generation on an iron storage protein scaffold

RSC Advances ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 5551-5559
Author(s):  
Brenda S. Benavides ◽  
Silvano Valandro ◽  
Donald M. Kurtz
Keyword(s):  
Heavy Chain ◽  
Platinum Nanoparticles ◽  
Storage Protein ◽  
Iron Storage ◽  
Protein Scaffold ◽  
H2 Generation ◽  
Iron Storage Protein

An assembly of platinum nanoparticles produced by Fe(ii) reduction of Pt(ii) and stabilized by human heavy chain ferritin's native catalysis of Fe(ii)(aq) autoxidation functions as an efficient photosensitized H2 evolution catalyst.

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