scholarly journals Chemistry at the protein–mineral interface in L-ferritin assists the assembly of a functional (μ3-oxo)Tris[(μ2-peroxo)] triiron(III) cluster

2017 ◽  
Vol 114 (10) ◽  
pp. 2580-2585 ◽  
Author(s):  
Cecilia Pozzi ◽  
Silvia Ciambellotti ◽  
Caterina Bernacchioni ◽  
Flavio Di Pisa ◽  
Stefano Mangani ◽  
...  
Keyword(s):  
Oxidation Rate ◽  
Iron Oxidation ◽  
Nucleation Site ◽  
Iron Ions ◽  
Protein Interface ◽  
Mineral Formation ◽  
X Ray ◽  
Protein Cage ◽  
Iron Mineral ◽  
Anionic Cluster

X-ray structures of homopolymeric L-ferritin obtained by freezing protein crystals at increasing exposure times to a ferrous solution showed the progressive formation of a triiron cluster on the inner cage surface of each subunit. After 60 min exposure, a fully assembled (μ3-oxo)Tris[(μ2-peroxo)(μ2-glutamato-κO:κO′)](glutamato-κO)(diaquo)triiron(III) anionic cluster appears in human L-ferritin. Glu60, Glu61, and Glu64 provide the anchoring of the cluster to the protein cage. Glu57 shuttles incoming iron ions toward the cluster. We observed a similar metallocluster in horse spleen L-ferritin, indicating that it represents a common feature of mammalian L-ferritins. The structures suggest a mechanism for iron mineral formation at the protein interface. The functional significance of the observed patch of carboxylate side chains and resulting metallocluster for biomineralization emerges from the lower iron oxidation rate measured in the E60AE61AE64A variant of human L-ferritin, leading to the proposal that the observed metallocluster corresponds to the suggested, but yet unobserved, nucleation site of L-ferritin.

Non-uniform distribution of dopant iron ions in TiO2 nanocrystals probed by X-ray diffraction, Raman scattering, photoluminescence and photocatalysis

2015 ◽  
Vol 3 (8) ◽  
pp. 1846-1853 ◽  
Author(s):  
S. Manu ◽  
M. Abdul Khadar
Keyword(s):  
Raman Scattering ◽  
Uniform Distribution ◽  
Semiconductor Nanocrystals ◽  
Iron Ions ◽  
X Ray Diffraction ◽  
Tio2 Nanocrystals ◽  
X Ray ◽  
Practical Applications ◽  
Mechanism Operative

The phenomenon of ‘self-purification’ is a real mechanism operative in nanocrystals and this should be taken into account while doping semiconductor nanocrystals with external impurities for practical applications.

Reaction pathways of iron-sulfide mineral formation: an in situ X-ray diffraction study

2018 ◽  
Vol 30 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Min-Yu Lin ◽  
Yen-Hua Chen ◽  
Jey-Jau Lee ◽  
Hwo-Shuenn Sheu
Keyword(s):  
Diffraction Study ◽  
Iron Sulfide ◽  
Sulfide Mineral ◽  
Reaction Pathways ◽  
Mineral Formation ◽  
X Ray Diffraction ◽  
X Ray

Evidence of Variations in Atomic Distribution in Disordered Mixed Metal Hydroxides

MRS Advances ◽  
2019 ◽  
Vol 4 (33-34) ◽  
pp. 1843-1850
Author(s):  
Wen Rong ◽  
Sarah Stepan ◽  
Rodney D. L. Smith
Keyword(s):  
Transition Metal Oxides ◽  
Iron Ions ◽  
X Ray Diffraction ◽  
Metal Hydroxides ◽  
X Ray ◽  
Mixed Metal ◽  
Apparent Solubility ◽  
Fundamental Understanding ◽  
Double Hydroxides ◽  
Mixed Metal Hydroxides

ABSTRACTNumerous fabrication protocols are known to yield transition metal oxides with structures related to layered double hydroxides, but the effect of fabrication protocol on the uniformity of mixed-metal compositions remain largely unexplored. We have analysed the apparent solubility limits and the structural implications of iron ions in nickel hydroxide lattices for materials prepared by four different fabrication protocols. Opposing shifts in the (100) and (001) reflection in powder X-ray diffraction results revealed a contraction of the nickel lattice upon successful incorporation of iron, with Ni-M distances exhibiting an apparently linear decrease with respect to iron content. This feature revealed the amount of iron incorporated into nickel-based materials to be dependent on fabrication protocol, varying from apparently negligible concentrations to over fifty atomic percent. The dependency of structure on fabrication protocols provides a handle to improve fundamental understanding of catalytically relevant coordination environments.

scholarly journals Molecular Packaging of Biocatalysts Using a Robust Protein Cage

2020 ◽  
Author(s):  
Nikola Lončar ◽  
Henriette J. Rozeboom ◽  
Linda E. Franken ◽  
Marc C. A. Stuart ◽  
Marco Fraaije
Keyword(s):  
Electron Microscopy ◽  
Expression System ◽  
Size Exclusion ◽  
Oligomeric Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Protein Cage ◽  
Size Exclusion Effect ◽  
Exclusion Effect

In this paper, we report on the discovery of a novel, robust protein cage (encapsulin) that we could use for packaging various biocatalysts. We have elucidated the structure of the stable encapsulin by electron microscopy and X-ray diffraction. Furthermore, we developed an effective expression system for the encapsulin and a facile protocol for preparing encapsulated enzymes. By packaging and testing various enzymes (varying in size, oligomeric structure, and cofactor type) we demonstrate that, through encapsulation, the enzymes become significantly more stable. We also provide evidence that the pores of the encapsulin, through a size-exclusion effect, can modulate the substrate acceptance profile of an encapsulated enzyme.

A Structure-Based Assembly Screen of Protein Cage Libraries in Living Cells: Experimentally Repacking a Protein–Protein Interface To Recover Cage Formation in an Assembly-Frustrated Mutant

Biochemistry ◽  
2018 ◽  
Vol 57 (5) ◽  
pp. 604-613 ◽  
Author(s):  
Thomas A. Cornell ◽  
Maziar S. Ardejani ◽  
Jing Fu ◽  
Stephanie H. Newland ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Living Cells ◽  
Protein Interface ◽  
Protein Cage

Wettability and Nanotribological Response of Silicon Surfaces Functionalized by Ion Implantation

2012 ◽  
Vol 730-732 ◽  
pp. 257-262
Author(s):  
Bruno Nunes ◽  
Sergio Magalhães ◽  
Nuno Franco ◽  
Eduardo Alves ◽  
Ana Paula Serro ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Ion Implantation ◽  
Silicon Surfaces ◽  
Iron Ions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Scanning Electron

Aiming to improve the nanotribological response of Si-based materials we implanted silicon wafers with different fluences of iron ions (up to 2x1017 cm-2). Implantation was followed by annealing treatments at temperatures from 550°C to 1000°C. The implanted surfaces were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and wettability tests. Then, samples were submitted to AFM-based nanowear tests. We observe an increase of both hidrophobicity and and wear resistance of the implanted silicon, indicating that ion implantation of Si can be a route to be deeper explored in what concerns tribomechanical improvement of Si.

scholarly journals Operando X-Ray Absorption Spectroscopy Shows Iron Oxidation Is Concurrent with Oxygen Evolution in Cobalt-Iron (Oxy)hydroxide Electrocatalysts

2018 ◽  
Vol 57 (39) ◽  
pp. 12840-12844 ◽  
Author(s):  
Lisa J. Enman ◽  
Michaela Burke Stevens ◽  
Meir Haim Dahan ◽  
Michael R. Nellist ◽  
Maytal Caspary Toroker ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Absorption Spectroscopy ◽  
Iron Oxidation ◽  
X Ray ◽  
Cobalt Iron ◽  
X Ray Absorption

Fabrication of Semiconductor Nano-particles in the Protein Cage of Apoferritin

2005 ◽  
Vol 873 ◽  
Author(s):  
Kenji Iwahori ◽  
Keiko Yoshizawa ◽  
Masahiro Muraoka ◽  
Ichiro Yamashita
Keyword(s):  
Chemical Reaction ◽  
Reaction System ◽  
Nano Particles ◽  
Internal Cavity ◽  
Reaction Parameters ◽  
Synthesis System ◽  
X Ray ◽  
Protein Cage ◽  
High Resolution Tem ◽  
Chemical Reaction System

AbstractWe specially designed a slow chemical reaction system to synthesize the zinc selenide nanoparticles (ZnSe NPs), in the cavity of the cage-shaped protein, apoferritin. The newly designed chemical synthesis system for ZnSe NPs makes the chemical reaction of compound semiconductor element ions dramatically slow, resulting in that ZnSe NPs can be synthesized in the internal cavity of the apoferritin. The ZnSe NPs synthesized by the optimized reaction parameters are efficiently produced in the aqueous solution. The UVVis spectrum analysis of synthesized ZnSe-ferritin suggests that the formation of ZnSe nuclei in the apoferritin cavity takes about 6 hours by using our slow chemical reaction system. The synthesized ZnSe NPs were characterized by high resolution TEM, X-ray powder diffraction (XRD) and Energy Dispersive Spectrometory (EDS) and it was revealed that the synthesized NPs are a collection of cubic ZnSe crystals.

scholarly journals Additively Manufactured NiTi and NiTiHf Alloys: Estimating Service Life in High-Temperature Oxidation

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2104 ◽  
Author(s):  
Hediyeh Dabbaghi ◽  
Keyvan Safaei ◽  
Mohammadreza Nematollahi ◽  
Parisa Bayati ◽  
Mohammad Elahinia
Keyword(s):  
High Temperature ◽  
Oxidation Rate ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Early Stage ◽  
Niti Alloy ◽  
Temperature Oxidation ◽  
X Ray ◽  
Rate Law ◽  
Parabolic Rate

In this study, the effect of the addition of Hf on the oxidation behavior of NiTi alloy, which was processed using additive manufacturing and casting, is studied. Thermogravimetric analyses (TGA) were performed at the temperature of 500, 800, and 900 °C to assess the isothermal and dynamic oxidation behavior of the Ni50.4Ti29.6Hf20 at.% alloys for 75 h in dry air. After oxidation, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to analyze the oxide scale formed on the surface of the samples during the high-temperature oxidation. Two stages of oxidation were observed for the NiTiHf samples, an increasing oxidation rate during the early stage of oxidation followed by a lower oxidation rate after approximately 10 h. The isothermal oxidation curves were well matched with a logarithmic rate law in the initial stage and then by parabolic rate law for the next stage. The formation of multi-layered oxide was observed for NiTiHf, which consists of Ti oxide, Hf oxide, and NiTiO3. For the binary alloys, results show that by increasing the temperature, the oxidation rate increased significantly and fitted with parabolic rate law. Activation energy of 175.25 kJ/mol for additively manufactured (AM) NiTi and 60.634 kJ/mol for AM NiTiHf was obtained.

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