Quantum Magnetism of the Iron Core in Ferritin Proteins: A Re-Evaluation of the Giant-Spin Model

The electron–electron, or zero-field interaction (ZFI) in the electron paramagnetic resonance (EPR) of high-spin transition ions in metalloproteins and coordination complexes, is commonly described by a simple spin Hamiltonian that is second-order in the spin S: ℋ=[2−(+1)/3+(2−2). Symmetry considerations, however, allow for fourth-order terms...

Ferritin-Based Single-Electron Devices

We report on the fabrication of single-electron devices based on horse-spleen ferritin parti-cles. At low temperatures the current vs. voltage characteristics are stable, enabling the acquisition of reproducible data that establishes the Coulomb blockade as the main transport mechanism through them. Excellent agreement between the...

Maximum iron loading of ferritin: half a century of sustained citation distortion

Analysis of citation networks in biomedical research has indicated that belief in a specific scientific claim can gain unfounded authority through citation bias (systematic ignoring of papers that contain content conflicting with a claim), amplification (citation to papers that don't contain primary data), and invention (citing content but...

Iron loading is a prominent feature of activated microglia in Alzheimer’s disease patients

Brain iron accumulation has been found to accelerate disease progression in amyloid-β(Aβ) positive Alzheimer patients, though the mechanism is still unknown. Microglia have been identified as key players in the disease pathogenesis, and are highly reactive cells responding to aberrations such as increased iron levels. Therefore, using...

Quantification of different iron forms in the aceruloplasminemia brain to explore iron-related neurodegeneration

Aims: Aceruloplasminemia is an ultra-rare neurodegenerative disorder associated with massive brain iron deposits, of which the molecular composition is unknown. We aimed to quantitatively determine the molecular iron forms in the aceruloplasminemia brain, and to illustrate their influence on iron-sensitive MRI metrics. Methods: The...

Towards an understanding of the electron paramagnetic resonance spectra of the ferritin core: A study of human liver ferritin

A technique that can be used in the study of the magnetic properties of ferritin is electron paramagnetic resonance (EPR), which is sensitive to the magnetic moments of unpaired electrons.<br/><br/>The magnetic properties of human liver ferritin were studied using 9 GHz EPR, with which temperature dependent spectra were acquired in the following...

Phosphate and arsenate removal efficiency by thermostable ferritin enzyme from Pyrococcus furiosus using radioisotopes

Oxo-anion binding properties of the thermostable enzyme ferritin from Pyrococcus furiosus were characterized with radiography. Radioisotopes 32P and 76As present as oxoanions were used to measure the extent and the rate of their absorption by the ferritin. Thermostable ferritin proved to be an excellent system for rapid phosphate and arsenate...

Magnetic force microscopy: Quantitative issues in biomaterials

Magnetic force microscopy (MFM) is an atomic force microscopy (AFM) based technique in which an AFM tip with a magnetic coating is used to probe local magnetic fields with the typical AFM spatial resolution, thus allowing one to acquire images reflecting the local magnetic properties of the samples at the nanoscale. Being a well established tool...

The Amyloid Precursor Protein (APP) Does Not Have a Ferroxidase Site in Its E2 Domain

The ubiquitous 24-meric iron-storage protein ferritin and multicopper oxidases such as ceruloplasmin or hephaestin catalyze oxidation of Fe(II) to Fe(III), using molecular oxygen as oxidant. The ferroxidase activity of these proteins is essential for cellular iron homeostasis. It has been reported that the amyloid precursor protein (APP) also...

Iron-Storage Mechanism of Ferritin

Storage of Fe(III) is a common mechanism by which the cellular machinery controls the availability of Fe(II) and Fe(III) for biosynthesis of iron-containing cofactors of enzymes which are involved in several essential biological processes, including oxidative phosphorylation. The conserved 24-meric iron-storage protein ferritin has been...

A novel mechanism of iron-core formation by Pyrococcus furiosus archaeoferritin, a member of an uncharacterized branch of the ferritin-like superfamily

Storage of iron in a nontoxic and bioavailable form is essential for many forms of life. Three subfamilies of the ferritin-like superfamily, namely, ferritin, bacterioferritin, and Dps (DNA-binding proteins from starved cells), are able to store iron. Although the function of these iron-storage proteins is constitutive to many organisms to...

Inhibition and stimulation of formation of the ferroxidase center and the iron core in Pyrococcus furiosus ferritin

Ferritin is a ubiquitous iron-storage protein that has 24 subunits. Each subunit of ferritins that exhibit high Fe(II) oxidation rates has a diiron binding site, the socalled ferroxidase center (FC). The role of the FC appears to be essential for the iron-oxidation catalysis of ferritins. Studies of the iron oxidation by mammalian, bacterial,...

Catalysis of iron core formation in Pyrococcus furiosus ferritin

The hollow sphere-shaped 24-meric ferritin can store large amounts of iron as a ferrihydrite-like mineral core. In all subunits of homomeric ferritins and in catalytically active subunits of heteromeric ferritins a diiron binding site is found that is commonly addressed as the ferroxidase center (FC). The FC is involved in the catalytic Fe(II)...

Structural and functional studies of the iron storage protein ferritin from Pyrococcus furiosus

This research focuses on the iron storage protein ferritin. Ferritin is a protein involved in iron homeostasis by storing Fe(II) excess in the form of an Fe(III) mineral core in the presence of oxygen and by releasing iron during iron deficiency. Ferritins are vital for human health. Their malfunction may lead among other diseases to anemia,...

EPR studies of recombinant horse L-chain apoferritin and its mutant (E 53,56,57,60 Q) with haemin

Crystal structure of the ferritin from the hyperthermophilic archaeal anaerobe Pyrococcus furiosus