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39 citations found for Oshima,

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The crystal structures of the two thermally equilibrated conformational isomers of the epoxide 1',5'-dimethyl­spiro[10,11-dihydro-5H-dibenzo[a,d]cyclo­heptene-5,8'-4'-oxatricyclo[5.1.0.03,5]octane]-2',6'-dione, C23H20O3, have been determined by X-ray diffraction. In the tricyclic dione skeleton, the oxirane and cyclo­propane rings adopt an anti structure with respect to the conjunct quinone frame. The spiro-linked 10,11-dihydro-5H-dibenzo[a,d]cyclo­heptene ring of the major isomer has a fairly twisted boat form, folding opposite to the adjoining cyclo­propane methyl substituent, whereas the seven-membered ring of the minor isomer has an almost ideal twist-boat form, inversely folding to the side of the relevant methyl group. The conformational structures of these isomers have been compared with those of the corresponding isomers of the unepoxidized homobenzoquinone.

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Acta Cryst. (1996). A52, C233
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Acta Cryst. (1993). A49, c73-c74
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Acta Cryst. (2014). A70, C1560
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In pharmaceutical sciences, the crystal structure is of primary importance because it influences drug efficacy. Due to difficulties of growing a large single crystal suitable for the single crystal X-ray diffraction analysis, powder diffraction method is widely used. In powder method, two-dimensional diffraction information is projected onto one dimension, which impairs the accuracy of the resulting crystal structure. To overcome this problem, we recently proposed a novel method of fabricating a magnetically oriented microcrystal array (MOMA), a composite in which microcrystals are aligned three-dimensionally in a polymer matrix. The X-ray diffraction of the MOMA is equivalent to that of the corresponding large single crystal, enabling the determination of the crystal lattice parameters and crystal structure of the embedded microcrytals.[1-3] Because we make use of the diamagnetic anisotropy of crystal, those crystals that exhibit small magnetic anisotropy do not take sufficient three-dimensional alignment. However, even for these crystals that only align uniaxially, the determination of the crystal lattice parameters can be easily made compared with the determination by powder diffraction pattern. Once these parameters are determined, crystal structure can be determined by X-ray powder diffraction method. In this paper, we demonstrate possibility of the MOMA method to assist the structure analysis through X-ray powder and single crystal diffraction methods. We applied the MOMA method to various microcrystalline powders including L-alanine, 1,3,5-triphenyl benzene, and cellobiose. The obtained MOMAs exhibited well-resolved diffraction spots, and we succeeded in determination of the crystal lattice parameters and crystal structure analysis.

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A pseudo single crystal of sucrose (monoclinic, P21) was prepared and the origin of its twin orientation is discussed.

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A submicrometre-area photoelectron spectroscopy system that uses a multi-layer-coated Schwarzschild objective as the soft X-ray microbeam optics has been developed. The system is located at an undulator beamline (BL-16U) at the Photon Factory in the High Energy Accelerator Research Organization. By knife-edge measurement, the microbeam size was estimated to be 160 nm at the sample position using a 25-75% criterion. Photoelectron spectral measurements revealed that the Fermi edge width was 0.12 eV, which means that the instrumental resolution was 0.05 eV, after removing the natural broadening of the Fermi edge at room temperature. This system offers both high energy resolution and high spatial resolution.

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A thermophilic bacterial homologue of mitoNEET (a mammalian mitochondrial outer membrane protein) from T. thermophilus HB8 (open reading frame TTHA0026; Tth-NEET0026) has been identified as a water-soluble prototypal [2Fe-2S] protein and crystallized. The bipyramidal crystals of the recombinant Tth-NEET0026 diffracted to 1.80 Å resolution using synchrotron radiation.

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In the title compound, C12H15Cl2NO, the piperidine ring adopts a chair conformation. An intra­molecular O-H...N hydrogen bond is observed. The packing of the mol­ecules in the crystal structure is stabilized by [pi]-[pi] inter­actions and Cl...Cl contacts.

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In the title compound, [Cu(C12H14Cl2NO)2], the CuII atom is four-coordinated in a distorted square-planar geometry by two N atoms and two O atoms from two 2,4-dichloro-6-(piperidin-1-ylmeth­yl)phenolate ligands. The dihedral angle between the N/Cu/O coordination planes is 16.53 (9)°.

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A system has been developed for the real-time analysis of surface reactions during molecular beam epitaxial growth which uses photoelectron spectroscopy with VUV light taken from synchrotron radiation. This system consists of a synchrotron radiation beamline and growth/analysis apparatus in which photoelectron spectroscopy is performed with sub-second time resolution. In this system, photoelectron spectra are measured in sequence by a `non-scanning' measurement method that enables the acquisition of snapshot photoelectron spectra using a multi-channel detector. This non-scanning measurement method was enabled by equipping an electric field correction grid. This system was used to monitor the photoelectron spectra of a GaSb(001) surface.

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Acta Cryst. (2008). A64, C133
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The structure of the title compound, C21H20O2, was determined by X-ray analysis. The results revealed that the 2,5-dioxocyclohexane skeleton is in a half-chair conformation, with torsion angles C(2)-C(1)-C(6)-C(5) -1.5 (3) and C(2)-C(3)-C(4)-C(5) -36.5 (3)° on account of the fused cyclopropane ring, which locates the 4-methyl group in an equatorial position. The plane of the endo-phenyl group was also found to be essentially parallel to the fused C(1)-C(6) bond.

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Cryogenic structure analysis has been applied on IPMDH to find out the physical difference of the thermostability of the native and chimeric mutant.

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Acta Cryst. (2017). A73, C1174
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The crystal structure of a hypothetical RNA 2'-O-ribose methyltransferase from T. thermophilus (RrmA) has been determined at 2.4 Å resolution and a deep trefoil knot has been found for the first time.

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A photoemission electron microscopy measurement system on insulating samples was established at the BL17SU beamline of SPring-8 by utilizing an Au pattern evaporation technique combined with photon-induced surface modification.

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Acta Cryst. (2014). A70, C851
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Innexin is a molecular component of invertebrate gap junctions, which have an important role in neural and muscular electrical activity in invertebrates. Although the structure of vertebrate connexin26 was revealed by X-ray crystallography [1], the structure of innexin channels remains poorly understood. To study the structure of innexin gap junction channels, we expressed and purified Caenorhabditis elegans innexin-6 (INX-6) gap junction channels, and characterized their molecular dimensions and channel permeability using electron microscopy (EM) and a fluorescent dye transfer assay, respectively [2]. Negative-staining and thin-section EM of isolated INX-6 gap junction plaques revealed a loosely packed hexagonal lattice. We performed single particle analysis of purified INX-6 channels with negative-staining and cryo EM. Based on the negative-stain EM images, the class average of the junction form had a longitudinal height of 220 Å, a channel diameter of 110 Å in the absence of detergent micelles, and an extracellular gap space of 60 Å, whereas the class average of the hemichannels had diameters of up to 140 Å in the presence of detergent micelles. Cryo EM images revealed rotational peaks that could be related to the INX-6 subunits. Structural analysis of the reconstituted INX-6 channels with single particle analysis and electron tomography suggested that the oligomeric number of the INX-6 channel was distinct from that of the dodecameric connexin channel. Dye transfer experiments indicated that the INX-6-GFP-His channels were permeable to 3-kDa and 10-kDa dextran-conjugated tracers. These findings indicate that INX-6 channels have a characteristic oligomer component that differs from that in connexin gap junction channels.


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