[en] Neutron quasi-Laue diffraction data (2 A resolution) from tetragonal hen egg-white lysozyme were collected in ten days with neutron imaging plates. The positions of 960 hydrogen atoms in the molecule and 157 bound water molecules, were determined. The distinctive nature of hydrogen atoms and bound water molecules in the lysozyme molecule was discussed. (author)

[en] Experimental strategy and setup for the 100 ps time-resolved X-ray absorption spectroscopy (TR-XAS) is presented. X-ray positional active feedback combined with a figure-of-merit scan of the laser beam position was employed as a key technique. It is shown that the pump-probe TR-XAS technique using the X-ray pulse structure of synchrotron radiation sources is a powerful tool to investigate dynamics of the electronic state and molecular structure of non-crystalline samples. A TR-XAS measurement of a photo-induced spin crossover reaction of the tris (1,10-phenanthroline)iron(II) complex in water is presented. (author)

[en] The structures of many typical endohedral metallofullerenes have been reported by the powder X-ray analysis. For example, the report of the trimetallorullerene Sc₃C₈₂ has shown that the endohedral structure is Sc₃(a)C₈₂, this being widely accepted. However, the recent ¹³C NMR spectroscopy and X-ray single crystal analysis have revealed that the structure of Sc₃C₈₂ is not Sc₃(a)C₈₂ but Sc₃C₂(a)C₈₀. This may suggest that the endohedral structures reported from the powder X-ray study are not always reliable even in a qualitative sense. (author)

[en] We report on the Fermi surface mapping of heavy element crystals using Compton scattering, which has been possible by the recent advent of intense high energy synchrotron radiation sources. Fermi surface mapping provides us insights for long range distortions or charge density waves in crystals. Two examples are shown : The first one is Fermi surface mapping of the η-Mo₄O₁₁ low-dimensional conductor. A clear nesting vector is observed in the Fermi surfaces that have experimentally been obtained. The second example is Fermi surface study of Ba_1-xK_xBiO₃. A clear feature of the Fermi surface nesting is observed across the transition between the distorted (insulating) and non-distorted (metallic) phases. (author)

[en] Picosecond time-resolved X-ray experiments using synchrotron radiation sources are becoming general and powerful tools to explore structural dynamics of condensed matters in material and biological sciences. The beam line NW14A is a newly constructed undulator beam line for 100-ps time-resolved X-ray experiments at the Photon Factory Advanced Ring, KEK. This beam line was designed to conduct a wide variety of time-resolved X-ray measurements, such as time-resolved X-ray diffraction, scattering and absorption. The beam line has been operational for two years, and current status of the beam line and scientific activities utilizing shock-induced lattice deformation will be presented. (author)

[en] Intercellular signaling is one of the most essential properties exhibited in multicellular organisms. Gap junction is a structure to allow direct intercellular communication. Here, we have determined the crystal structure of human gap junction channel at 3.5A. The crystal belonging to a monoclinic space group of C2 has six molecules in an asymmetric unit. The initial phases were obtained at 8.0A resolution by the single isomorphous replacement method combined with the molecular replacement method with a hypothetical structure consisting of four helices. Phase extension was performed up to 3.5A resolution by six-fold non-crystallographic symmetry averaging and multicrystal averaging. Anormalous dispersion signals from selenium atoms of a seleno-methionines derivative crystal and from sulfur atoms of the native crystal uniquely located amino acids and disulfide bonds in the electron density map. Consequently the trans-membrane parts a typical four-helix bundle, which was quite different from that previously proposed. The two extracellular loops in each monomer that interact with the opposing units have three intramolecular disulfide bonds. The first loop makes the wall of the channel pore and the second loop, which extends to overlay the first loop, makes subtype specific interaction. From our structure, the molecular basis of the specific junctional interaction is revealed. (author)

[en] Many protein structures have been determined by X-ray crystallography and deposited with the Protein Data Bank. However, these structures at usual resolution (1.5< d<3.0 A) are insufficient in their precision and quantity for elucidating the molecular mechanism of protein functions directly from structural information. Several studies at ultra-high resolution (d<0.8 A) have been performed with synchrotron radiation in the last decade. The highest resolution of the protein crystals was achieved at 0.54 A resolution for a small protein, crambin. In such high resolution crystals, almost all of hydrogen atoms of proteins and some hydrogen atoms of bound water molecules are experimentally observed. In addition, outer-shell electrons of proteins can be analyzed by the multipole refinement procedure. However, the influence of X-rays should be precisely estimated in order to derive meaningful information from the crystallographic results. In this review, we summarize refinement procedures, current status and perspectives for ultra high resolution protein crystallography. (author)

[en] In order to collect proper diffraction data from outstanding micro-crystals, a brand-new data collection system should be designed to provide high signal-to noise ratio in diffraction images. SPring-8 and KEK-PF are currently developing two micro-beam beamlines for Targeted Proteins Research Program by MEXT of Japan. The program aims to reveal the structure and function of proteins that are difficult to solve but have great importance in both academic research and industrial application. At SPring-8, a new 1-micron beam beamline for protein micro-crystallography, RIKEN Targeted Proteins Beamline (BL32XU), is developed. At KEK-PF a new low energy micro-beam beamline, BL-1A, is dedicated for SAD micro-crystallography. The two beamlines will start operation in the end of 2010. The present status of the research and development for protein micro-crystallography will be presented. (author)

[en] The anomalous X-ray scattering (AXS) coupled with a model calculation using reverse Monte Carlo (RMC) simulation, has recently received much attention for analyzing the detailed structure for disordered materials. The usefulness of this advanced AXS-RMC method is demonstrated with some selected examples of molten AgBr, Zr₅₀Cu₅₀ metallic glass and Zr₇₀Pd₃₀ metallic glass. (author)

[en] History of the study of the Earth's deep interior was reviewed. In order to understand Earth's deep interior from the view point of materials science, X-ray diffraction under high pressure and high temperature played very important role. Use of synchrotron radiation dramatically advanced this experimental technique and it is now possible to make precise X-ray study under the P-T conditions corresponding even to the center of the Earth. In order to clarify the behavior of light elements such as hydrogen, however, studies using neutron diffraction are also required. A new neutron beam line dedicated for high-pressure science is constructed at J-PARC and is now ready for use. (author)