Crystal structure of glucuronic acid dehydrogeanse from Chromohalobacter salexigens

2011 ◽  
Vol 80 (1) ◽  
pp. 314-318 ◽  
Author(s):  
Jae-Woo Ahn ◽  
Shin Youp Lee ◽  
Sangwoo Kim ◽  
Suk Min Kim ◽  
Sun Bok Lee ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Glucuronic Acid ◽  
Chromohalobacter Salexigens

scholarly journals Crystal structure of GH30-7 endoxylanase C from the filamentous fungus Talaromyces cellulolyticus

2020 ◽  
Vol 76 (8) ◽  
pp. 341-349
Author(s):  
Yusuke Nakamichi ◽  
Tatsuya Fujii ◽  
Masahiro Watanabe ◽  
Akinori Matsushika ◽  
Hiroyuki Inoue
Keyword(s):  
Crystal Structure ◽  
Glucuronic Acid ◽  
Catalytic Domain ◽  
Catalytic Efficiency ◽  
Structural Features ◽  
Hydroxyl Group ◽  
Glycoside Hydrolase Family ◽  
Talaromyces Cellulolyticus ◽  
Cellulose Binding ◽  
Hydrolase Family

GH30-7 endoxylanase C from the cellulolytic fungus Talaromyces cellulolyticus (TcXyn30C) belongs to glycoside hydrolase family 30 subfamily 7, and specifically releases 22-(4-O-methyl-α-D-glucuronosyl)-xylobiose from glucuronoxylan, as well as various arabino-xylooligosaccharides from arabinoxylan. TcXyn30C has a modular structure consisting of a catalytic domain and a C-terminal cellulose-binding module 1 (CBM1). In this study, the crystal structure of a TcXyn30C mutant which lacks the CBM1 domain was determined at 1.65 Å resolution. The structure of the active site of TcXyn30C was compared with that of the bifunctional GH30-7 xylanase B from T. cellulolyticus (TcXyn30B), which exhibits glucuronoxylanase and xylobiohydrolase activities. The results revealed that TcXyn30C has a conserved structural feature for recognizing the 4-O-methyl-α-D-glucuronic acid (MeGlcA) substituent in subsite −2b. Additionally, the results demonstrated that Phe47 contributes significantly to catalysis by TcXyn30C. Phe47 is located in subsite −2b and also near the C-3 hydroxyl group of a xylose residue in subsite −2a. Substitution of Phe47 with an arginine residue caused a remarkable decrease in the catalytic efficiency towards arabinoxylan, suggesting the importance of Phe47 in arabinoxylan hydrolysis. These findings indicate that subsite −2b of TcXyn30C has unique structural features that interact with arabinofuranose and MeGlcA substituents.

scholarly journals A fused [3.3.0]-neoglycoside lactone derived from glucuronic acid

2013 ◽  
Vol 69 (9) ◽  
pp. 1062-1066 ◽  
Author(s):  
Matthew W. Schombs ◽  
Ryan A. Davis ◽  
James C. Fettinger ◽  
Jacquelyn Gervay-Hague
Keyword(s):  
Crystal Structure ◽  
Natural Products ◽  
Biological Activity ◽  
Glucuronic Acid ◽  
Anomeric Effect ◽  
Next Generation ◽  
One Pot ◽  
Insight Into

The bridged next-generation aminoglycoside (neoglycoside), 1-deoxy-1-[(methoxy)methylamino)]-2,5-di-O-triethylsilyl-β-D-glucofuranurono-γ-lactone {systematic name: (3S,3aS,5R,6R,6aS)-5-[methoxy(methyl)amino]-3,6-bis[(triethylsilyl)oxy]-2,3,3a,5,6,6a-hexahydrofuro[3,2-b]furan-2-one}, C20H41NO6Si2, was synthesized in a one-pot manner from commercially available D-glucuronic acid. This structure supports the properties associated with the anomeric effect for furanosides and can be employed to provide insight into the mechanisms by which alkoxyamine-appended natural products derive their enhanced biological activity. To the best of our knowledge, this is the first published crystal structure of a bicyclic neoglycoside and is the first neoglycoside to be completely and unambiguously characterized.

scholarly journals Crystal structure of rubidium peroxide ammonia disolvate

2017 ◽  
Vol 73 (2) ◽  
pp. 200-202
Author(s):  
Tobias Grassl ◽  
Nikolaus Korber
Keyword(s):  
Crystal Structure ◽  
Nitrogen Atom ◽  
Low Temperature ◽  
Liquid Ammonia ◽  
Glucuronic Acid ◽  
Mirror Plane ◽  
Acta Cryst ◽  
Low Temperature Crystallization ◽  
Peroxide Bond ◽  
Temperature Crystallization

The title compound, Rb2O2·2NH3, has been obtained as a reaction product of rubidium metal dissolved in liquid ammonia and glucuronic acid. As a result of the low-temperature crystallization, a disolvate was formed. To our knowledge, only one other solvate of an alkali metal peroxide is known: Na2O2·8H2O has been reported by Grehlet al.[Acta Cryst.(1995), C51, 1038–1040]. We determined the peroxide bond length to be 1.530 (11) Å, which is in accordance with the length reported by Bremm & Jansen [Z. Anorg. Allg. Chem.(1992),610, 64–66]. One of the ammonia solvate molecules is disordered relative to a mirror plane, with 0.5 occupancy for the corresponding nitrogen atom.

Crystal Structure Determination of Glycerol-Containing Lipids from Electron Diffraction Data. Use of Analog Compounds Based upon Configurational Isomers of Cyclopentane-1, 2, 3-TRIOL

1977 ◽  
Vol 35 ◽  
pp. 24-25
Author(s):  
Douglas L. Dorset ◽  
Anthony J. Hancock
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Crystal Surface ◽  
Coherent Scattering ◽  
Crystal Structure Determination ◽  
Electron Diffraction Data ◽  
Polar Group ◽  
Axis Orientation

Lipids containing long polymethylene chains were among the first compounds subjected to electron diffraction structure analysis. It was only recently realized, however, that various distortions of thin lipid microcrystal plates, e.g. bends, polar group and methyl end plane disorders, etc. (1-3), restrict coherent scattering to the methylene subcell alone, particularly if undistorted molecular layers have well-defined end planes. Thus, ab initio crystal structure determination on a given single uncharacterized natural lipid using electron diffraction data can only hope to identify the subcell packing and the chain axis orientation with respect to the crystal surface. In lipids based on glycerol, for example, conformations of long chains and polar groups about the C-C bonds of this moiety still would remain unknown.One possible means of surmounting this difficulty is to investigate structural analogs of the material of interest in conjunction with the natural compound itself. Suitable analogs to the glycerol lipids are compounds based on the three configurational isomers of cyclopentane-1,2,3-triol shown in Fig. 1, in which three rotameric forms of the natural glycerol derivatives are fixed by the ring structure (4-7).

Spherulitic crystal growth in the prodissoconch larval of Crassostrea virginica

1983 ◽  
Vol 41 ◽  
pp. 518-519
Author(s):  
George G. Cocks ◽  
Louis Leibovitz ◽  
DoSuk D. Lee
Keyword(s):  
Crystal Structure ◽  
Crassostrea Virginica ◽  
Crystal Orientation ◽  
Developmental Changes ◽  
Gastrula Stage ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Stages Of Growth ◽  
Early Stages ◽  
Initial Deposition

Our understanding of the structure and the formation of inorganic minerals in the bivalve shells has been considerably advanced by the use of electron microscope. However, very little is known about the ultrastructure of valves in the larval stage of the oysters. The present study examines the developmental changes which occur between the time of conception to the early stages of Dissoconch in the Crassostrea virginica(Gmelin), focusing on the initial deposition of inorganic crystals by the oysters.The spawning was induced by elevating the temperature of the seawater where the adult oysters were conditioned. The eggs and sperm were collected separately, then immediately mixed for the fertilizations to occur. Fertilized animals were kept in the incubator where various stages of development were stopped and observed. The detailed analysis of the early stages of growth showed that CaCO3 crystals(aragonite), with orthorhombic crystal structure, are deposited as early as gastrula stage(Figuresla-b). The next stage in development, the prodissoconch, revealed that the crystal orientation is in the form of spherulites.

Transmission Electron Microscopy studies of the vacancy ordering in YSI2-X thin films

1991 ◽  
Vol 49 ◽  
pp. 562-563
Author(s):  
F.-R. Chen ◽  
T. L. Lee ◽  
L. J. Chen
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Thin Films ◽  
Diffraction Pattern ◽  
Annealing Temperature ◽  
Lattice Mismatch ◽  
Si Substrate ◽  
Metal Thin Films ◽  
Transmission Electron ◽  
Vacancy Ordering

YSi2-x thin films were grown by depositing the yttrium metal thin films on (111)Si substrate followed by a rapid thermal annealing (RTA) at 450 to 1100°C. The x value of the YSi2-x films ranges from 0 to 0.3. The (0001) plane of the YSi2-x films have an ideal zero lattice mismatch relative to (111)Si surface lattice. The YSi2 has the hexagonal AlB2 crystal structure. The orientation relationship with Si was determined from the diffraction pattern shown in figure 1(a) to be and . The diffraction pattern in figure 1(a) was taken from a specimen annealed at 500°C for 15 second. As the annealing temperature was increased to 600°C, superlattice diffraction spots appear at position as seen in figure 1(b) which may be due to vacancy ordering in the YSi2-x films. The ordered vacancies in YSi2-x form a mesh in Si plane suggested by a LEED experiment.

Crystal Structure Analysis of Cu-Zr Alloys by Convergent Beam Diffraction

1981 ◽  
Vol 39 ◽  
pp. 354-355
Author(s):  
A. F. Marshall ◽  
J. W. Steeds ◽  
D. Bouchet ◽  
S. L. Shinde ◽  
R. G. Walmsley
Keyword(s):  
Crystal Structure ◽  
Point Group ◽  
Intermetallic Phase ◽  
Three Dimensional ◽  
Crystal Structure Analysis ◽  
Ion Milling ◽  
Composition And Structure ◽  
Unit Cells ◽  
Sputter Deposited ◽  
Convergent Beam

Convergent beam electron diffraction is a powerful technique for determining the crystal structure of a material in TEM. In this paper we have applied it to the study of the intermetallic phases in the Cu-rich end of the Cu-Zr system. These phases are highly ordered. Their composition and structure has been previously studied by microprobe and x-ray diffraction with sometimes conflicting results.The crystalline phases were obtained by annealing amorphous sputter-deposited Cu-Zr. Specimens were thinned for TEM by ion milling and observed in a Philips EM 400. Due to the large unit cells involved, a small convergence angle of diffraction was used; however, the three-dimensional lattice and symmetry information of convergent beam microdiffraction patterns is still present. The results are as follows:1) 21 at% Zr in Cu: annealed at 500°C for 5 hours. An intermetallic phase, Cu3.6Zr (21.7% Zr), space group P6/m has been proposed near this composition (2). The major phase of our annealed material was hexagonal with a point group determined as 6/m.

High resolution STEM imaging study on high Tc superconductor YBa2CuaO7-x

1988 ◽  
Vol 46 ◽  
pp. 882-883
Author(s):  
H.-J. Ou ◽  
J. M. Cowley
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Grain Boundary ◽  
Strong Field ◽  
Imaging Study ◽  
Structure Defects ◽  
High Tc ◽  
High Tc Superconductor ◽  
Diffraction Patterns ◽  
Lattice Planes

Using the dedicate VG-HB5 STEM microscope, the crystal structure of high Tc superconductor of YBa2Cu3O7-x has been studied via high resolution STEM (HRSTEM) imaging and nanobeam (∽3A) diffraction patterns. Figure 1(a) and 2(a) illustrate the HRSTEM image taken at 10' times magnification along [001] direction and [100] direction, respectively. In figure 1(a), a grain boundary with strong field contrast is seen between two crystal regions A and B. The grain boundary appears to be parallel to a (110) plane, although it is not possible to determine [100] and [001] axes as it is in other regions which contain twin planes [3]. Following the horizontal lattice lines, from left to right across the grain boundary, a lattice bending of ∽4° is noticed. Three extra lattice planes, indicated by arrows, were found to terminate at the grain boundary and form dislocations. It is believed that due to different chemical composition, such structure defects occur during crystal growth. No bending is observed along the vertical lattice lines.

Crystal structure images of large gold clusters and growing crystals by HRTEM

1984 ◽  
Vol 42 ◽  
pp. 428-429
Author(s):  
L.R. Wallenberg ◽  
J.-O. Bovin ◽  
G. Schmid
Keyword(s):  
Crystal Structure ◽  
Nucleation And Growth ◽  
Close Packing ◽  
Gold Clusters ◽  
Molecular Weight Determination ◽  
Growth Mechanisms ◽  
Starting Point ◽  
Different Types ◽  
Nucleation And Growth Mechanisms ◽  
Points Of View

Metallic clusters are interesting from various points of view, e.g. as a mean of spreading expensive catalysts on a support, or following heterogeneous and homogeneous catalytic events. It is also possible to study nucleation and growth mechanisms for crystals with the cluster as known starting point.Gold-clusters containing 55 atoms were manufactured by reducing (C6H5)3PAuCl with B2H6 in benzene. The chemical composition was found to be Au9.2[P(C6H5)3]2Cl. Molecular-weight determination by means of an ultracentrifuge gave the formula Au55[P(C6H5)3]Cl6 A model was proposed from Mössbauer spectra by Schmid et al. with cubic close-packing of the 55 gold atoms in a cubeoctahedron as shown in Fig 1. The cluster is almost completely isolated from the surroundings by the twelve triphenylphosphane groups situated in each corner, and the chlorine atoms on the centre of the 3x3 square surfaces. This gives four groups of gold atoms, depending on the different types of surrounding.

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