Nihon Kessho Gakkaishi
Online ISSN : 1884-5576
Print ISSN : 0369-4585
ISSN-L : 0369-4585
Volume 55, Issue 5
Displaying 1-12 of 12 articles from this issue
Review Articles
  • Hiroshi KIHARA, Masaji SHINJO, Yoshitaka MATSUMURA
    2013 Volume 55 Issue 5 Pages 271-277
    Published: October 31, 2013
    Released on J-STAGE: November 01, 2013
    JOURNAL FREE ACCESS
    Early events of protein folding have been investigated by a cryo-stopped-flow method with ultraviolet circular dichroism, fluorescence and X-ray solution scattering as probes. We found that α-helices were formed very rapidly as a folding nucleus within the dead-time of the stopped-flow apparatus. In the case of ubiquitin containing α-helix and β-structure, the folding took place via α-helix-rich intermediate, contrary to the previous hypothesis of 2-state transition. This was also the case of Src SH3 domain protein containing only β-structure and other proteins so far investigated. The intermediate structure of Src SH3 domain protein folding was calculated by using a SAXS-MD program.
    In the studies of three homologous SH3 domain proteins (Src, Fyn and PI3K), we found that these proteins are folded via a different folding pathways.
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Articles
  • Kengo OKA, Masaki AZUMA, Shigeo MORI
    2013 Volume 55 Issue 5 Pages 278-284
    Published: October 31, 2013
    Released on J-STAGE: November 01, 2013
    JOURNAL FREE ACCESS
    Polarization rotation is the key for interpretation of the piezoelectricity in Pb(Ti1-xZrx)O3(PZT)and other piezoelectric ceramics. We found the monoclinic phase in BiCo1-xFexO3x~0.7)that is isostructural with the low temperature phase of PZT at the morphotropic phase boundary(MPB). Precise structural analysis by electron diffraction and powder synchrotron X-ray diffraction revealed that the monoclinic perovskite BiCo1-xFexO3 exhibits Cm symmetry and showed polarization rotation as functions of composition and temperature. The second order structural transition from tetragonal to monoclinic structures was accompanied by a rotation of the polarization vector from the[001]to[111]directions of a pseudo cubic cell.
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  • Hiromi TANJI, Umeharu OHTO, Toshiyuki SHIMIZU
    2013 Volume 55 Issue 5 Pages 285-289
    Published: October 31, 2013
    Released on J-STAGE: November 01, 2013
    JOURNAL FREE ACCESS
    The Toll-like receptors(TLRs)are a family of pattern-recognition receptors that recognize pathogen-associated molecular patterns and activate innate immune system. TLR8 is activated by single-stranded RNA or synthetic imidazoquinoline compounds. We determined the crystal structures of unliganded and liganded TLR8 to clarify signaling and activation mechanism of TLR8.
    TLR8 monomer was ring-shaped structure in which N- and C-termini interacted directly. Both in the unliganded and liganded forms, TLR8 formed m-shaped dimer in which two C termini converged in the middle. Ligands were located in the two equivalent positions in the dimerization interface related by the non-crystallographic two-fold axis. The C-termini of the two TLR8 protomers were separated by 53 Å in the unliganded form; whereas, C-termini of the two monomers were brought into close proximity(~30 Å)in the liganded form, which would enable the subsequent dimerization of the TIR domains and downstream signaling.
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  • Takao SHIMIZU, Hiroki TANIGUCHI, Tomoyasu TANIYAMA, Mitsuru ITOH
    2013 Volume 55 Issue 5 Pages 290-295
    Published: October 31, 2013
    Released on J-STAGE: November 01, 2013
    JOURNAL FREE ACCESS
    An unconventional pseudo-tetragonal crystal structure is found in a BaTiO3 epitaxial thin film grown on a (110)SrTiO3 substrate. The unique crystal structure of the BaTiO3 film, which is markedly different from the bulk tetragonal structure, is caused by the nearly uniaxial strain due to the different strain relaxation along [001] and [110] axes.
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  • Shintaro YASUI, Hiroshi FUNAKUBO, Osami SAKATA
    2013 Volume 55 Issue 5 Pages 296-301
    Published: October 31, 2013
    Released on J-STAGE: November 01, 2013
    JOURNAL FREE ACCESS
    Novel perovskite-type Bi-based piezoelectric materials which was discovered by high pressure synthesis were fabricated by MOCVD method. We also suggested a piezoresponse measurement system using synchrotron X-ray for In-situ measurement of “Polarization - Lattice strain - Electric field” at a same time.
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  • Yohei SATO, Masami TERAUCHI, Wataru INAMI, Akira YOSHIASA
    2013 Volume 55 Issue 5 Pages 302-307
    Published: October 31, 2013
    Released on J-STAGE: November 01, 2013
    JOURNAL FREE ACCESS
    Electronic structure of hexagonal diamond(h-DIA)was investigated by using high energyresolution electron energy-loss spectroscopy(EELS)based on transmission electron microscopy. The dielectric function of h-DIA was derived by Kramers-Kronig analysis of the EELS spectrum. Core electron excitation spectrum of h-DIA revealed density of states in conduction band,which was different distribution from that of cubic diamond. The electronic structure of h-DIA was experimentally revealed for the first time.
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  • Shogo KAWAGUCHI, Hiroki ISHIBASHI, Yoshiki KUBOTA
    2013 Volume 55 Issue 5 Pages 308-314
    Published: October 31, 2013
    Released on J-STAGE: November 01, 2013
    JOURNAL FREE ACCESS
    We have investigated the incommensurate crystal structure of the spinel CuV2S4, which exhibits incommensurate charge-density wave at 90 K, using the synchrotron powder diffraction technique. It is found that the crystal structure at 70 K has an orthorhombic unit cell with the superspace-group Imm2(0β0)with a modulation vector q=0.7391(5)b*. By Rietveld analysis including the incommensurate modulation along the b-axis, large static atomic displacements were found at the positions of V atoms, suggesting that V atoms play an important role in a charge-density wave transition. We have found the formation of V clusters, and arrangements of the clusters form a gradation pattern along the b-axis.
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  • Noritake YASUOKA
    2013 Volume 55 Issue 5 Pages 315-
    Published: October 31, 2013
    Released on J-STAGE: November 01, 2013
    JOURNAL FREE ACCESS
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  • 2013 Volume 55 Issue 5 Pages 316-318
    Published: October 31, 2013
    Released on J-STAGE: November 01, 2013
    JOURNAL FREE ACCESS
    Download PDF (695K)
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