scholarly journals Structure of EPCR in a non-canonical conformation

2021 ◽  
Author(s):  
Jacinto Lopez-Sagaseta ◽  
Elena Erausquin Arrondo ◽  
Adela Rodriguez Fernandez
Keyword(s):  
Protein C ◽  
Critical Role ◽  
Conformational Flexibility ◽  
Biological Functions ◽  
X Ray Diffraction ◽  
Endothelial Protein C Receptor ◽  
Apparent Effect ◽  
X Ray ◽  
A Site ◽  
Structural Motion

Structural motion and conformational flexibility are often linked to biological functions of proteins. Whether the endothelial protein C receptor (EPCR), like other molecules, is vulnerable to folding transitions or might adopt alternative conformations remains unknown. The current understanding points to a rigid molecular structure suitable for binding of its ligands, like the anticoagulant protein C, or the CIDRα1 domains of Plasmodium falciparum. In this study, we have identified a novel conformation of EPCR, captured by X-ray diffraction analyses, whereby Tyr154 shows a dramatically altered structural arrangement, likely incompatible with protein C binding. Biolayer interferometry analysis confirms previous results supporting a critical role for this position in protein C binding. Importantly, the conformational change has no apparent effect in the bound lipid. We conclude these findings reveal a site of conformational vulnerability in EPCR and inform a highly malleable region that could modulate EPCR functions.

Chemical and Electrochemical Heteroepitaxial Growth of Chalcogenide Semiconductors from Solutions

1996 ◽  
Vol 451 ◽  
Author(s):  
D. Lincot ◽  
M. J. Furlong ◽  
M. Froment ◽  
R. Cortes ◽  
M. C. Bernard
Keyword(s):  
Heteroepitaxial Growth ◽  
X Ray Diffraction ◽  
Basic Principles ◽  
Lattice Match ◽  
X Ray ◽  
Chalcogenide Semiconductors ◽  
Influence Of Temperature On ◽  
Deposition Processes ◽  
A Site ◽  
Site Selective

ABSTRACTChalcogenide semiconductors have been deposited epitaxially from aqueous solutions either chemically or electrochemically at growth rates of up to 0.7 μmhr−1. After recalling the basic principles of these deposition processes, results are presented concerning chemically deposited CdS on InP, GaP and CuInSe2 substrates, electrodeposited CdTe on InP, and CdSAnP heterostructures. Characterisation of these structures by RHEED, TEM, HRTEM, and glazing angle X ray diffraction allows to analyse the effects of substrate orientation, polarity, lattice match plus the influence of temperature on epitaxial growth. These results are discussed in terms of self organisation and a site selective growth mechanisms due to the free enegy of formation of each compound.

scholarly journals Crystal Structure Refinements of Four Monazite Samples from Different Localities

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1028 ◽  
Author(s):  
M. Mashrur Zaman ◽  
Sytle M. Antao
Keyword(s):  
Crystal Structure ◽  
Electron Probe ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Large Unit Cell ◽  
A Site

This study investigates the crystal chemistry of monazite (APO4, where A = Lanthanides = Ln, as well as Y, Th, U, Ca, and Pb) based on four samples from different localities using single-crystal X-ray diffraction and electron-probe microanalysis. The crystal structure of all four samples are well refined, as indicated by their refinement statistics. Relatively large unit-cell parameters (a = 6.7640(5), b = 6.9850(4), c = 6.4500(3) Å, β = 103.584(2)°, and V = 296.22(3) Å3) are obtained for a detrital monazite-Ce from Cox’s Bazar, Bangladesh. Sm-rich monazite from Gunnison County, Colorado, USA, has smaller unit-cell parameters (a = 6.7010(4), b = 6.9080(4), c = 6.4300(4) Å, β = 103.817(3)°, and V = 289.04(3) Å3). The a, b, and c unit-cell parameters vary linearly with the unit-cell volume, V. The change in the a parameter is large (0.2 Å) and is related to the type of cations occupying the A site. The average <A-O> distances vary linearly with V, whereas the average <P-O> distances are nearly constant because the PO4 group is a rigid tetrahedron.

Metal-Controlled Assembly Tuning Coordination Polymers with Flexible 2-(1H-imidazole-1-yl)acetic Acid (Hima)

2006 ◽  
Vol 59 (9) ◽  
pp. 647 ◽  
Author(s):  
Yong-Tao Wang ◽  
Gui-Mei Tang ◽  
Da-Wei Qin
Keyword(s):  
Coordination Polymers ◽  
Weak Interactions ◽  
Critical Role ◽  
Three Dimensional ◽  
Supramolecular Network ◽  
Water Medium ◽  
New Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Supramolecular Networks

Three new inorganic–organic coordination polymers based on a versatile linking unit 2-(1H-imidazole-1-yl)acetate (Hima) and divalent Mn(ii), Ni(ii), and Cu(ii) ions, exhibiting two kinds of two dimensionalities with different topological structures, have been prepared in water medium and structurally characterized by single-crystal X-ray diffraction analysis. Reaction of MnCl2·4H2O and Ni(NO3)2·6H2O with Hima yielded neutral two-dimensional (2D) coordination polymers [M(ima)2]n, M = Mn(ii) 1, and Ni(ii) 2 with isostructural 2D coordination polymers possessing (3,6) topology structures, which further stack into three-dimensional (3D) supramolecular networks through C–H···O weak interactions. However, when Cu(NO3)2·4H2O was used, a neutral 2D coordination polymer [Cu(ima)2]n 3 consisting of rhombus units was generated, which showed a 3D supramolecular network through C–H···O weak interactions. Among these polymers, the building block ima anion exhibits different coordination modes. These results indicate that the versatile nature of this flexible ligand, together with the coordination preferences of the metal ions, plays a critical role in construction of these novel coordination polymers. Spectral and thermal properties of these new materials have also been investigated.

Phase Diagram of the W-doped Pb(Zn1/3Nb2/3)O3–BaTiO3– PbTiO3 System Around a Morphotropic Phase Boundary Composition

2002 ◽  
Vol 17 (5) ◽  
pp. 1085-1091 ◽  
Author(s):  
W. Z. Zhu ◽  
M. Yan ◽  
A. L. Kholkin ◽  
P. Q. Mantas ◽  
J. L. Baptista
Keyword(s):  
High Temperature ◽  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrical Neutrality ◽  
Phase Boundary Composition ◽  
A Site ◽  
Successive Phase

The morphotropic phase boundary (MPB) composition that is characterized by the coexistence of rhombohedral and tetragonal phases in the Pb(Zn1/3Nb2/3)O3–BaTiO3– PbTiO3 system was modified by W-doping at the B site of a perovskite structural block. To maintain the electrical neutrality, creation of A-site vacancies was intentionally introduced in the formulation of the examined compositions. Incorporation of W ions was revealed to stabilize the tetragonal phase against the rhombohedral one, shifting the MPB toward the PZN-rich end at room temperature. High-temperature x-ray diffraction examination in combination with dielectric measurements discloses two successive phase transitions as a sample is cooled from high temperature, namely, paraelectric cubic to ferroelectric rhombohedral followed by ferroelectric rhombohedral to ferroelectric tetragonal. W addition appears to suppress the first transition while promoting the second one.

scholarly journals X-ray Crystallographic Study of Ranaconitine

2011 ◽  
Vol 6 (11) ◽  
pp. 1934578X1100601
Author(s):  
Yang Li ◽  
Jun-Hui Zhou ◽  
Gui-Jun Han ◽  
Min-Juan Wang ◽  
Wen-Ji Sun ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Diffraction Analysis ◽  
Critical Role ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
Crystallographic Study ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The crystal structure of natural diterpenoid alkaloid ranaconitine isolated from Aconitum sinomontanum Nakai has been determined by single crystal X-ray diffraction analysis. The crystal presents a monoclinic system, space group C2 with Z = 4, unit cell dimensions a = 30.972(19) Å, b = 7.688(5) Å, and c = 19.632(12) Å. Moreover, the intermolecular O–H···O hydrogen bonds and weak π-π interactions play a critical role in expanding the dimensionality.

Quaternary intermetallics RE2Pt3Ga4In (RE=Y, Gd-Tm) – intergrowth structures of NdRh2Sn4 and TiNiSi related slabs

2020 ◽  
Vol 235 (4-5) ◽  
pp. 117-125
Author(s):  
Myroslava Horiacha ◽  
Maximilian K. Reimann ◽  
Jutta Kösters ◽  
Vasyl‘ I. Zaremba ◽  
Rainer Pöttgen
Keyword(s):  
Single Crystals ◽  
High Frequency ◽  
Magnetic Moments ◽  
Intermetallic Phases ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Arc Melting ◽  
Intergrowth Structures ◽  
A Site

AbstractThe quaternary gallium-rich intermetallic phases RE2Pt3Ga4In with RE = Y and Gd-Tm were synthesized by arc-melting of the elements and subsequent annealing. Small single crystals were obtained by high-frequency annealing of the samples in sealed tantalum ampoules. The polycrystalline samples were characterized through their X-ray powder patterns. The RE2Pt3Ga4In phases crystallize with a site ordering variant of the orthorhombic Y2Rh3Sn5 type, space group Cmc 21. The structures of Gd2Pt3Ga4In, Dy2Pt3Ga4.14In0.86, Er2Pt3Ga4.17In0.83 and Tm2Pt3Ga4.21In0.79 were refined from single-crystal X-ray diffraction data. The single crystals reveal small homogeneity ranges RE2Pt3Ga4±xIn1±x. The striking geometrical structural building units are slightly distorted trigonal prisms around the three crystallographically independent platinum atoms: Pt1@RE4Ga2, Pt2@RE2Ga4 and Pt3@RE2Ga2In2. Based on these prismatic building units, the RE2Pt3Ga4In structures can be described as intergrowth variants of TiNiSi and NdRh2Sn4 related structural slabs. Temperature dependent magnetic susceptibility studies of Gd2Pt3Ga4In and Tb2Pt3Ga4In show Curie-Weiss behavior and the experimental magnetic moments confirm stable trivalent gadolinium respectively terbium. Gd2Pt3Ga4In and Tb2Pt3Ga4In order antiferromagnetically at TN = 15.8(1) and 26.0(1) K. Magnetization curves at 3 K show field-induced spin reorientations.

The Properties of Modified Polysulfonamide Fabrics with Lamellar Magnesium Hydroxide Crystals

2013 ◽  
Vol 8 (2) ◽  
pp. 155892501300800
Author(s):  
Hui Ma ◽  
Linping Zhang ◽  
Hong Xu ◽  
Dan Wang ◽  
Xiaoyan Zhang ◽  
...  
Keyword(s):  
Magnesium Hydroxide ◽  
Inductively Coupled Plasma ◽  
Heat Insulation ◽  
Critical Role ◽  
Atomic Absorption Spectrometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Inductively Coupled ◽  
Carboxylic Acid Groups ◽  
Flammability Test

Lamellar magnesium hydroxide crystals were prepared successfully on the surface of polysulfonamide fibers with carboxylic acid groups. The polysulfonamide fabrics with Mg(OH)2 crystals were characterized by Scanning electron microscopy, Inductively coupled plasma atomic absorption spectrometer X-ray diffraction, Vertical flammability test and Thermalgravimetric analysis. The vertical flammability test showed that the damaged length of original polysulfonamide fabrics was 34mm, while that of the polysulfonamide fabrics with Mg(OH)2 crystals (treated by 7.5% NaOH solutions) was 14mm. In addition, the Mg (OH)2 crystals played a critical role in the improvement of thermal stability and heat insulation of polysulfonamide fabrics.

Equilibrium phase diagrams in the system CuO–PbO–Ag

1995 ◽  
Vol 10 (11) ◽  
pp. 2933-2937 ◽  
Author(s):  
H.K. Liu ◽  
S.X. Dou ◽  
M. Ionescu ◽  
Z.B. Shao ◽  
K.R. Liu ◽  
...  
Keyword(s):  
High Temperature Superconductor ◽  
Eutectic Reaction ◽  
Critical Role ◽  
Equilibrium Phase ◽  
Eutectic Point ◽  
X Ray Diffraction ◽  
X Ray ◽  
Liquid Phases ◽  
Tie Lines ◽  
Xrd Techniques

Silver has played a critical role for the fabrication of metal/high temperature superconductor composites. Phase equilibrium and microstructure in the ternary PbO-CuO-Ag system have been investigated using differential thermal analysis (DTA), thermogravimetry (TG), scanning electron microscope (SEM), and x-ray diffraction (XRD) techniques. Composition versus temperature diagrams have been established for these systems in air. In the ternary CuO-PbO-Ag system, there is a eutectic reaction CuO + PbO + Ag = L at 750 °C and a composition of 12.04 mol % Ag, 16.35 mol % CuO, and 72.62 mol % PbO. Two immiscible regions near the two binary tie lines PbO-Ag and CuO-Ag were detected. No binary or ternary compound was detected in these systems. SEM and EDS results confirm the presence of two liquid phases and the eutectic point

Synthesis of One-Dimensional Chalcogenides by a Novel Hydrothermal Process

2004 ◽  
Vol 99-100 ◽  
pp. 203-208 ◽  
Author(s):  
Hui Zhang ◽  
De Ren Yang ◽  
Yujie Ji ◽  
Xiang Yang Ma ◽  
Jin Xu ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Critical Role ◽  
Hydrothermal Process ◽  
Nucleation And Growth ◽  
Saed Pattern ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Selected Area Electron Diffraction

A TGA assisted hydrothermal process was employed to prepare chalcogenide nanorods. The different morphology of CdS nanomaterials prepared with and without the TGA assisted hydrothermal process indicates that TGA plays a critical role in controlling the nucleation and growth of CdS nanomaterials. The paper makes a preliminary presentation of the mechanisms of preparation of chalcogenide nanostructures with and without the use of the TGA assisted hydrothermal synthesis. FeS nanorods and nanoparticles have been prepared by the TGA assisted and without the TGA assisted hydrothermal process, respectively, which confirmed the proposed mechanism. X-ray diffraction (XRD) shows that the nanorods are of orthorhombic structure, and selected area electron diffraction (SAED) pattern showed that the FeS nanorods were single crystalse. Further investigation for the synthesis of other chalcogenides will be undertaken in order to confirm the proposed mechanism.

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