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.

The resolution of individual protein subunits in ferritin

1978 ◽  
Vol 36 (2) ◽  
pp. 182-183
Author(s):  
William H. Massover
Keyword(s):  
Electron Microscopy ◽  
Storage Protein ◽  
Quaternary Structure ◽  
Negative Staining ◽  
Variable Amount ◽  
X Ray Diffraction ◽  
Iron Storage ◽  
Protein Subunits ◽  
X Ray ◽  
Iron Storage Protein

The technique of negative staining has been of very great value for directly determining the quaternary structure of individual multimeric proteins and viruses. In this regard, the iron-storage protein,, ferritin, is a notable exception for not having had its subunits unambiguously resolved by negative staining. Each ferritin molecule (d= 120Å) has an outer shell of 24 protein subunits (MW= 18,500) surrounding a variable amount of mineralized iron; published x-ray diffraction studies have not yet defined individual monomers in the polymeric shell. Claims that single subunits have been visualized in ferritin by electron microscopy (e.g.,6) all appear to be of highly doubtful validity since the phase granularity of the dried stain and supporting film has the same dimension as the presumed subunits; apparent subunits are readily visualized in defocused images, but are no longer discernable when brought closer to exact focus.

Paracrystalline Arrays of Horse Spleen Ferritin

1982 ◽  
Vol 40 ◽  
pp. 366-367
Author(s):  
William H. Massover
Keyword(s):  
Present Report ◽  
X Ray Diffraction ◽  
Iron Storage ◽  
X Ray ◽  
Planar Arrays ◽  
Tetragonal Crystals ◽  
The Many ◽  
Horse Spleen Ferritin ◽  
Initial Results ◽  
Iron Storage Protein

Each molecule of the major iron-storage protein, ferritin, has a well-known architecture, with a 24-subunit protein shell (d=130 Å) surrounding a central cavity (d=75Å) that can be filled with a variable amount of mineralized ferric iron. By manipulating the salt composition and amount, horse spleen ferritin can be induced to form large cubic or tetragonal crystals usable for structure analysis by x-ray diffraction. Despite the success of the x-ray diffraction approach, further procedures must be developed for use with structural studies of the many ferritins that resist ready crystallization (i.e., those from neoplastic cells). Ultrastructural analysis of biomacromolecules is greatly facilitated if they can be prepared in the form of thin crystalline or paracrystal l ine layers (e.g., 2). Although ferritin mixed with certain lipids has been shown to organize into ordered planar arrays, there have been no reports about the preparation and electron microscope study of thin microcrystals of this metalloprotein. The present report describes our initial results with electron microscopy of ordered thin arrays of horse spleen ferritin.

Rectifying Behavior of Aligned ZnO Nanorods on Mg0.3Zn0.7O Thin Film Template

2011 ◽  
Vol 364 ◽  
pp. 35-39 ◽  
Author(s):  
Salina Muhamad ◽  
Abu Bakar Suriani ◽  
Mohamad Hafiz Mamat ◽  
Rafidah Ahmad ◽  
Mohamad Rusop
Keyword(s):  
Thin Film ◽  
Zno Nanorods ◽  
Thermionic Emission ◽  
Deposition Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hexagonal Shape ◽  
Semiconductor Junction ◽  
Vertically Aligned ◽  
Scanning Electron

Rectifying behavior more than 3 orders of aligned zinc oxide (ZnO) nanorods grown on Mg0.3Zn0.7O thin film template using chemical bath deposition method was observed, giving a barrier height of 0.75 eV, and the ideality factor achieved was almost 6, which was analyzed using thermionic emission theory. Field emission scanning electron microscope (FESEM) images revealed that the grown ZnO was in hexagonal shape, uniformly distributed and in vertically aligned form. The crystallinity of the sample being studied using X-ray diffraction (XRD), where the highest peak was found at (002) phase, confirming that high crytallinity of ZnO was attained. The effect of metal/semiconductor junction between metal and aligned ZnO nanorods was discussed in further details.

scholarly journals Synthesis and Characterization of CdS Slim Film Grown by CBD Method

2020 ◽  
Vol 5 (7) ◽  
pp. 170-172
Author(s):  
Vhadgal Gorakh Anna
Keyword(s):  
Living Arrangements ◽  
Uv Spectroscopy ◽  
X Ray Diffraction ◽  
Cadmium Sulfate ◽  
Morphological Attributes ◽  
X Ray ◽  
Hexagonal Shape ◽  
Cbd Method ◽  
The Ideal

Substance shower testimony strategy have been utilized to store Cadmium sulfide dainty film. The affect of the appropriate response temperature and PH is explored on this work. The introduction of CdS dainty film Cadmium Sulfate, Anomia, Thiourea and Double refined water is utilized as wellspring of material . Examining Electron microscopy (SEM ) is utilized for morphological attributes of CdS slender film. UV spectroscopy have been utilized for optical living arrangements of the CdS slender film .The band hole of CdS dainty film by methods for UV spectroscopy changed into 2.42 eV . The X-R diffraction investigation is affirmed that the CdS meager film were polycrystline with hexagonal shape the ideal direction of CdS slender film had been(002) and crystalline size 50nM .It changed into chose from the broadenings of corrousponding X-Ray diffraction tops by means of the utilization of Debye scherrer recipe.

scholarly journals Ag-induced a New Raman Mode in ZnO Microrods

2019 ◽  
Vol 25 (3) ◽  
pp. 227-230
Author(s):  
Jing WANG ◽  
Lina WANG ◽  
Meina WANG ◽  
Dan ZHOU ◽  
Yan MEI ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Raman Mode ◽  
X Ray Diffraction ◽  
Characteristic Mode ◽  
Raman Analysis ◽  
X Ray ◽  
Ag Doping ◽  
Si Substrates ◽  
Hexagonal Shape ◽  
Vapor Deposition Technique

The chemical vapor deposition technique was used to prepare the Ag doped ZnO microrods, which were located on Si substrates at two different positions.  The scanning electron microscopy revealed that the samples have a clear hexagonal shape. X-ray diffraction provided information about the preferential orientation along the c-axis. The Raman analysis revealed that a new Raman mode appears at 492 cm-1 due to Ag doping. As this mode has not been reported early, it could be used as a characteristic mode of Ag doping in Raman spectrum. The red shift of the E2 (high) mode proves the existence of tensile stress in the samples. DOI: http://dx.doi.org/10.5755/j01.ms.25.3.19130

Study of the magnetic and structural properties of Al–Cr codoped Y-type hexaferrite prepared via sol–gel auto-combustion method

2015 ◽  
Vol 29 (14) ◽  
pp. 1550090 ◽  
Author(s):  
O. Mirzaee ◽  
R. Mohamady ◽  
A. Ghasemi ◽  
Y. Alizad Farzin
Keyword(s):  
Magnetic Properties ◽  
Sol Gel ◽  
Combustion Method ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hexagonal Shape ◽  
Auto Combustion ◽  
Xrd Patterns ◽  
Cr Doping

Nanostructure of Y-type hexaferrite with composition of Sr 2 Ni 2 Al x/2 Cr x/2 Fe 12-x O 22 (where x are 0, 0.6, 1.2, 1.8, 2.4 and 3) were prepared by sol–gel auto-combustion method. The influence of Al and Cr doping on the structural and magnetic properties has been investigated. The X-ray diffraction (XRD) patterns confirm phase formation of Y-type hexaferrite. The microstructure and morphology of prepared samples were studied by high resolution field emission scanning electron microscope (FESEM) which shows the hexagonal shape for all of the samples. Magnetic properties were characterized using vibrating sample magnetometer (VSM). The magnetic results revealed that by increasing the Al and Cr to the structure, the coercivity was also increased from 840 Oe to 1160 Oe. Moreover it has been shown that with addition of dopants, saturation magnetization (Ms) and remnant magnetization (Mr) were decreased from 39.61 emu/g to 30.11 emu/g and from 17.51 emu/g to 14.62 emu/g, respectively, due to the entrance of nonmagnetic ions into Fe 3+ sites.

scholarly journals Ordering Phase Transition with Symmetry-Breaking from Disorder over Non-Equivalent Sites: Calorimetric and Crystallographic Study of Crystalline d-Sorbose

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 361
Author(s):  
Sakiko Iwagaki ◽  
Hiroki Kakuta ◽  
Yasuhisa Yamamura ◽  
Hideki Saitoh ◽  
Mafumi Hishida ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Phase Transitions ◽  
Structural Disorder ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Apparent Contradiction ◽  
X Ray ◽  
Thermal Anomalies ◽  
X Ray Crystallography ◽  
Main Transition

Phase transitions in the crystalline state of chiral sorbose were examined using precise heat capacity calorimetry and X-ray crystallography. The calorimetry established heat capacity below room temperature. Besides the known transition (main transition) at 199.5 K, the calorimetry detected plural thermal anomalies assignable to new phase transitions (around 210 K) and a glass transition (at ca. 120 K). The X-ray diffraction at low temperatures established the crystal structure of the lowest temperature phase. The identification of the broken symmetry upon the main transition solves an apparent contradiction that the structural disorder reported previously does not contribute seemingly to the symmetrization.

Effects of lithium, indium, and zinc on the lattice parameters of magnesium

2008 ◽  
Vol 23 (12) ◽  
pp. 3379-3386 ◽  
Author(s):  
A. Becerra ◽  
M. Pekguleryuz
Keyword(s):  
Solid Solution ◽  
Brillouin Zone ◽  
Electron Concentration ◽  
Axial Ratio ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vegard’S Law

The lattice parameters of magnesium solid-solution alloys with lithium, indium, and/or zinc have been determined via x-ray diffraction (XRD). Li decreased the axial ratio (c/a) of Mg from 1.624 to 1.6068 within 0–16 at.% Li. Indium increased the c/a of Mg to 1.6261 with increasing In toward 3.3 at.% while Zn showed no effect on c/a in the 0.2–0.7 at.% range. The effects were explained by electron overlap through the first Brillouin zone and by Vegard’s Law. A relationship was determined between electron concentration (e/a) and c/a as c/a = −15.6(e/a)2 + 60(e/a) − 55.8.

Fabrication and Characterization of In-Doped Zinc Oxide Nanodisks

2007 ◽  
Vol 121-123 ◽  
pp. 127-130
Author(s):  
Juan Liu ◽  
Yue Zhang ◽  
Jun Jie Qi ◽  
Yun Hua Huang ◽  
Xiao Mei Zhang
Keyword(s):  
Room Temperature ◽  
Thermal Evaporation ◽  
Graphite Powder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Uv Emission ◽  
Hexagonal Shape ◽  
Catalyst Morphology ◽  
Fabrication And Characterization

In-doped ZnO nanodisks were successfully fabricated by thermal evaporation Zn, In2O3 and graphite powder mixture without catalyst. Morphology, structures and components of ZnO nanodisks were investigated by SEM, HRTEM, EDS and X-Ray diffraction. ZnO nanodisks have perfect hexagonal shape, with 1~3μm size and 40~100 nm in thickness. The nanodisks are single-crystalline ZnO with wurtzite structure and In content of nanodisks reaches 2.2%. The growth along [0001] is suppressed leading to the formation of ZnO nanodisks. Room temperature photoluminescence spectra of the nanodisks shows that the UV emission peak blueshifts and becomes broader after doping.

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