Morphology and Magnetic Structure of the Ferritin Core during Iron Loading and Release by Magnetooptical and NMR Methods

Abstract

Ferritins are proteins, which serve as a storage and transportation capsule for iron inside living organisms. Continuously charging the proteins with iron and releasing it from the ferritin is necessary to assure proper management of these important ions within the organism. On the other hand, synthetic ferritins have great potential for biomedical and technological applications. In this work, the behavior of ferritin during the processes of iron loading and release was examined using multiplicity of the experimental technique. The quality of the protein's shell was monitored using circular dichroism, whereas the average size and its distribution were estimated from dynamic light scattering and transmission electron microscopy images, respectively. Because of the magnetic behavior of the iron mineral, a number of magnetooptical methods were used to gain information on the iron core of the ferritin. Faraday rotation and magnetic linear birefringence studies provide evidence that the iron loading and the iron-release processes are not symmetrical. The spatial organization of the mineral within the protein's core changes depending on whether the iron was incorporated into or removed from the ferritin's shell. Magnetic optical rotatory dispersion spectra exclude the contribution of the Fe(II)-composed mineral, whereas joined magnetooptical and nuclear magnetic resonance results indicate that no mineral with high magnetization appear at any stage of the loading/release process. These findings suggest that the iron core of loaded/released ferritin consists of single-phase, that is, ferrihydrite. The presented results demonstrate the usefulness of emerging magnetooptical methods in biomedical research and applications.

Switching of the mechanism of charge transport induced by phase transitions in tunnel junctions with large biomolecular cages

“…Interestingly, the iron oxide NPs inside E2-LFtn are dominated by Fe II rather than Fe III ions as reported for ferritin. 54,55 This observation suggests that the iron mineralisation process in E2-LFtn differs from that of ferritin which could be related to the differences in cavity size and spatial arrangement of the M-ferritin mimicking catalytic sites. 22 The ratio of the peak areas (R I = Fe II /Fe III ) for 3000Fe E2-LFtn decreases with decreasing T from 1.25 at 300 K to 0.50 at 120 K (Fig.…”

Enhanced Cellular Uptake of H-Chain Human Ferritin Containing Gold Nanoparticles

“…So far, side-chain conformational changes in the amino acid that interacts with Au +3 or Au 0 have been reported [28,51]. In addition, different authors have reported the conservation of the secondary structures of ferritin after iron incorporation to produce magnetoferritin, therefore maintaining the almost intact protein cage after iron mineralization [56][57][58][59]. Identical results were reported by Xiangyou Lui et al, revealing that ferritin with Pt nanoparticles does not have significant changes in the secondary structures of the protein, markedly α-helical [60].…”

How stable are the collagen and ferritin proteins for application in bioelectronics?

“…In case of the ferritin protein, the CD spectrum showed bands at 222 nm (ellipticity: -42.9 ± 5.7 mdeg), 203.9 nm (ellipticity: -24.3 ± 11 mdeg) and 197.9 nm (ellipticity: 8.2 ± 3 mdeg) (Fig 1B, black curve). The shape of the curve and magnitude of these far UV-CD bands suggest that ferritin protein has a substantial helical content and the polypeptide chains exist in an ordered structure [48,49]. For the protease-treated holoferritin, the bands observed at 222.1 nm, 202.8 nm and 198 nm (Fig 1B , red curve) indicate minimal shift in the band positions, although the ellipticity values, i.e., -30.7 ± 0.8 mdeg, -28.7 ± 2 mdeg and 14.6 ± 9 mdeg for the bands at 222.1 nm, 202.8 nm and 198 nm, respectively, are significantly altered.…”