Total reflection mirror and crystal monochromator are presented as two major optical elements in synchrotron radiation beamline. Reflectivity, typical X-ray mirrors used at SPring-8 beamlines, and sagittal and tangential focusing are shown for total reflection mirror. Energy range and energy resolution using crystal monochromator, geometry and mechanism for double-crystal monochromator, and cooling of first crystal from high heat load are shown briefly with the examples of SPring-8 standard beamlines. Photon flux through the beamline optics is also estimated with the effective band-width of monochromator.
As an introduction of a synchrotron radiation (SR) lecture-series for material science discipline, crystal structure analysis using SR X-ray diffraction is explained. This paper consists of three key words of SR; high brilliance, high resolution, and tunable incident X-ray energy. The former two key words realize precise crystal structural information by conventional methods. Application of resonant X-ray scattering method is able to determine the crystal structure which can not be able to be analyzed by conventional technique.
It is well known that hydrogen atoms in DNA play important roles for folding, stability, enzymatic function, and recognition via hydrogen bonds. A combination of X-ray and neutron diffraction study is a powerful technique to reveal hydrogen and hydration structures of DNA. Here, my present study of high resolution neutron crystallographic analysis of Z-DNA is described together with my previous X-ray analysis of chemically damaged DNA, in which hydrogen bonding pattern was converted so as to cause mutagenesis. These results illustrate complicated and artistic features of DNA structures.
SCFFbsl is a ubiquitin-ligase that plays a role in the endoplasmic reticulum-associated degradation pathway. Fbsl/Fbx2, a member of the F-box proteins, recognizes high-mannose oligosaccharides. The structure of the sugar-binding domain-chitobiose complex includes hydrogen bonds between Fbs1 and chitobiose and insertion of the methyl-group of chitobiose into a small hydrophobic pocket of Fbsl. We propose that Fbsl interacts with the chitobiose in unfolded N-glycoproteins, pointing the protein moiety toward E2 for ubiquitination.
The precise crystal structure of Zn4Sb3, which is one of the most efficient thermoelectric materials, has been determined by combination of Maximum Entropy Method and Rietveld analysis using synchrotron-radiation powder diffraction at SPring-8. The identification of Sb3- ions and Sb24- dimers reveals that Zn4Sb3 is a valence semiconductor with the ideal stoichiometry Zn13Sb10. The structure contains significantly disordered with zinc atoms distributed over multiple positions. The crystal structure of Zn4Sb3 in present study allows a general explanation of the thermal conductivity which explains the remarkable thermoelectric figure of merit.
The human malaria parasite Plasmodiiun falciparum is responsible for the death of more than a million people each year. Plasmodium falciparum S-adenosyl-L-homocysteine hydrolase (PfSAHH) inhibitors are expected to provide a new type of chemotherapeutic agent against malaria. Here we report the crystal structure of PfSAHH complexed with the reaction product adenosine. Knowledge of the structure in combination with a structural comparison with human SAHH (HsSAHH) revealed that a single amino acid substitution between the PfSAHH and HsSAHH accounts for the differential interactions with nucleoside inhibitors. The structure should provide opportunities to design selective PfSAHH inhibitors.
We successfully synthesized a novel high-silica zeolite CDS-1 by topotactic conversion from a new three-dimensional layered silicate PLS-1. The crystal structure of PLS-1 was determined from X-ray powder diffraction data. The framework of PLS-1 all composed of five membered-rings is consistent with a part of a ferrierite framework. We estimated that new microporous materials can be formed by a topotactic condensation between the layers of the PLS-1 with a layer structure consisting of face sharing of pentagonal cylinders. Then, available microporous structures were simulated by a molecular dynamics calculation. Experimentally, CDS-1 could be obtained by complete block dehydration-condensation. The structure of CDS-1 was determined by Rietveld refinements based on simulated models. The novel high-silica zeolite CDS-1, which has a novel topology including two-dimensional straight channels, is briefly described.