Modulated Structures and Superspace Groups (An Introduction to the Crystallographer's World)
By Akiji YAMAMOTO
Affiliation: National Institute for Research in Inorganic Materials
Address: Namiki, Tsukuba, Ibaraki, 305, Japan
The original paper [de Wolff, Acta Cryst. A30 777 (1974)] introducing a concept of higher-dimensional crystals and giving a basis of superspace groups will be reviewied.
Molecular Mechanism of Muscle Regulation - Structural Study of Troponin C in Complex with Troponin I Fragment (Article)
By Soichi TAKEDA, Dmitry G. Vassylyev, and Yuichiro MAEDA
Troponin (Tn), the complex of three subunits (TnC, TnI and TnT), plays a key role in calcium-dependent regulation of striated muscle contraction. In order to elucidate the interactions between the Tn subunits, we have determined the crystal structure of TnC in complex with the N-terminal fragment of TnI (TnI1-47) at 2.3-angstrom resolution. The TnC/TnI1-47 structure implies a mechanism of how Tn regulate the muscle contraction and suggests a unique a-helical regulatory TnI segment, which binds to the N-lobe of TnC in its calcium-bound comformation.
Unusual Ligand Structure of The Ni-Fe Active Center in Hydrogenase (Article)
By Yoshiki HIGUCHI1, Tatsuhiko YAGI2, and Noritake YASUOKA3
Affiliation: Department of Life Science, Faculty of Science, Himeji Institute of Technology3 and Shizuoka University2
Address: Kanaji 1472-2, Kamigori, Akogum, Hyogo 678-1297, Japan3 and 836 Oya, Shizuoka 422-8529, Japan2
E-mail: e-mail: email@example.com and firstname.lastname@example.org
The x-ray structure of the hydrogenase from Desulfovibrio vulgaris Miyazaki F has been solved at 1.8 Å resolution, and refined to a crystallographic R-factor of 0.229. The high resolution crystal structure enabled us to assign the non-protein ligands to Fe atom in the Ni-Fe site, and revealed the presence of a Mg center. From the nature of the electron density map, stereochemical geometry, and atomic parameters of the refined structure, the most probable candidates for the four ligands have been proposed to be diatomic SO, CO, CN molecules and one sulfur atom.
Structural Basis of Specific and Efficient Catalysis in Hematopoietic Prostaglandin D Synthase as an Glutathione S-Transferase (Article)
By Hideo AGO and Masashi MIYANOAbstract:
Crystal Chemistry of Novel Complex Vanadium Oxides with Layered Structures (Article)
By Yoshio OKA1 and Takeshi YAO2
Affiliation: Department of Natural Environment Sciences, Faculty of Integrated Human Studies1 and Graduate School of Energy Sciences2, Kyoto University
Address: Sakyo-ku, Kyoto 606-8501, Japan
E-mail: email@example.com and firstname.lastname@example.org
Some of complex vanadium (IV, V) oxides are categorized into bronze compounds that adopt open-frame structures with foreign metals in their interstitial sites. There can be a variety of open-frame structure types depending on sizes and amounts of foreign metals as well as on vanadium-oxygen compositions. Utilizing hydrothermal methods we have succeeded in synthesizing single crystals of new vanadium bronze compounds with layered structures. Here we describe crystal structures of the selected novel layered compounds of d-A0.5V2O5, s-A0.25V2O5·H2O, AxV3O8(VO)y·nH2O and Cs2V4O11. Each of these compounds exhibits interesting structural features such as interlayer metal distributions, novel layer frameworks and unusual vanadium-oxygen coordinations.
A New High Pressure Phase of SiO2 Formed by Hydrostatic Compression of Cristobalite -Effect of Non-hydrostatic Stress on the Crystal Lattice- (Article)
By Masaaki YAMAKATA1 and Takehiko YAGI2
Affiliation: SPring-81 and Institute for Solid State Physics, University of Tokyo2
Address: Mikazuki-cho, Sayou-gun, Hyogo 678-1298, Japan1
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Cristobalite was compressed under various degree of hydrostaticity in this work. It was clarified that, under high pressure, non-hydrostatic stress affects the crystal structure of high pressure polymorph. A new polymorph of SiO2 was formed under quasi-hydrostatic compression of cristobalite. While the crystal structure of this new polymorph is very similar to that of rutile-type, lattice parameters are different from that of stishovite. No systematic study to clarify the effects of non-hydrostatic stress has ever been made. The effect of non-hydrostatic stress on the crystal lattice was discussed in this paper.