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121.
Toshihiko Oka Hironari Kamikubo Fumio Tokunaga Janos K. Lanyi Richard Needleman Mikio Kataoka 《Photochemistry and photobiology》1997,66(6):768-773
Abstract— The single cysteine-containing bacteriorhodopsin mutants F27C, L100C, T170C, F171C and I222C were labeled with p -chloromercuribenzoic acid, which specifically reacts with sulfhydryl groups. These cysteines should be located at the cytoplasmic ends of the transmembrane helices A, C, F or G. We determined the positions of the bound mercury atoms by X-ray diffraction of purple membrane films, with better than 1 Å accuracy. The determined mercury positions were compared with the structural model from cryoelectron microscopy (N. Grigorieff, T. A. Ceska, K. H. Downing, J. M. Baldwin and R. Henderson, J. Mol. Biol 259, 393-421, 1996). Given that the distance between the mercury and the Cα atom of the cysteine in the xy plane must be shorter than 4.5 Å and that the mercury atom is located at the δ position, the positions obtained for the mercury labels agree with their expected positions from the structural model. The present results give a rationale for detecting structural changes upon illumination as shifts occur in the mercury label position. 相似文献
122.
Yasuhiro Suzuki Yuichi Tohmori Kazutoshi Kato Mitsuo Fukuda Hiromi Oohashi Satoshi Sekine Naoto Uchida Hiromu Toba Masaharu Horiguchi Toshihiko Sugie Yasuhumi Yamada 《Optical and Quantum Electronics》1998,30(3):141-159
Cost-effectiveness is essential in developing optical access network systems. To reduce system costs, both improved system and component technologies are required. Reducing the costs of optical devices and modules in an optical network unit is especially necessary. In this paper, the requirements for optical devices in optical access networks and modules are clarified. Moreover, we also review the recent progress in technologies for semiconductor optical devices and hybrid integration for low-cost optical modules in access networks. 相似文献
123.
Ameneh Sahraneshin Seiichi Takami Kimitaka Minami Daisuke Hojo Toshihiko Arita Tadafumi Adschiri 《Progress in Crystal Growth and Characterization of Materials》2012,58(1):43-50
Organic-functionalized nanoscale yttrium aluminum garnet (YAG) particles were synthesized via a simple rapid supercritical hydrothermal method in the presence of oleylamine and oleic acid as organic surface modifiers. The presence of the organic molecules resulted in the various morphologies of the produced YAG particles, including cubic, spherical and chainlike structures. Because of their hydrophobic surface character, as-synthesized particles were dispersible in organic solvents. 相似文献
124.
Naofumi Kozai Sachi Kawamura Tamotsu Kozaki Toshihiko Ohnuki Takahiro Sato Fumitaka Esaka 《Journal of solid state chemistry》2007,180(8):2279-2289
Fe2+-montmorillonite with Fe2+ ions occupying cation exchange sites is an ideal transformation product in bentonite buffer material. In our previous study on preparation and characterization of Fe2+-montmorillonite, the montmorillonite sample that adsorbed Fe2+ ions on almost all of the cation exchange sites was prepared using a FeCl2 solution under an inert gas condition [N. Kozai, Y. Adachi, S. Kawamura, K. Inada, T. Kozaki, S. Sato, H. Ohashi, T. Ohnuki, T. Banba, J. Nucl. Sci. Technol. 38 (2001) 1141]. In view of the unstable nature of iron(II) chemical species, this study attempted to determine the potential contaminant iron chemical species in the sample. Nondestructive elemental analysis revealed that a small amount of chloride ions remained dispersed throughout the clay particles. The chloride ion retention may be due to the adsorption of FeCl+ ion pairs in the initial FeCl2 solution and the subsequent containment of the Cl− ions that are dissociated from the FeCl+ ion pairs during excess salt removal treatment. Two explanations are advanced for the second process: the slow release of the remaining Cl− ions from the collapsed interlayer of the montmorillonite, and the transformation of a minor fraction of the remaining FeCl+ ion pairs to iron(III) hydroxide chloride complexes having low solubility. 相似文献
125.
Two-step synthesis of 1,2-dihydrocyclobuta[]isoquinolin-4(3H)-ones, novel cyclobutane-fused heterocycles, from 3-methoxy-2-methylisoquinolin-1(2H)-one and their reacion with olefins are described. 相似文献
126.
Chemiluminescence sequential injection immunoassay for vitellogenin using magnetic microbeads 总被引:2,自引:0,他引:2
A rapid and sensitive immunoassay for the determination of carp vitellogenin (Vg) is described. The method involves a sequential injection analysis (SIA) system equipped with a chemiluminescence detector and a samarium-cobalt magnet. An anti-Vg monoclonal antibody, immobilized on magnetic beads, was used as a solid support for the immunoassay. The introduction, trapping and release of the magnetic beads in the flow cell were controlled by a samarium-cobalt magnet and the flow of the carrier solution. The immunoassay was based on a sandwich immunoreaction of anti-Vg monoclonal antibody (primary antibody) on the magnetic beads, Vg, and the anti-Vg antibody labeled with horseradish peroxidase (HRP) (secondary antibody), and was based on a subsequent chemiluminescence reaction of HRP with hydrogen peroxide and p-iodophenol, in a luminol solution. The magnetic beads to which the primary antibody was immobilized were prepared by coupling the primary antibody with the magnetic beads after an agarose-layer on the surface of the magnetic beads was epoxidized. The primary antibody-immobilized magnetic beads were introduced, and trapped in the flow cell equipped with the samarium-cobalt magnet, a Vg sample solution, an HRP-labeled secondary antibody solution and the luminol solution were sequentially introduced into the flow cell based on an SIA programmed sequence. Chemiluminescence emission was monitored by means of a photomultiplier located at the upper side of the flow cell. The optimal incubation times both for the first and second immunoreactions were determined to be 20 min. A concave calibration curve was obtained between Vg concentration and chemiluminescence intensity when various concentrations of standard Vg samples (2–100 ng mL−1) were applied to the SIA system under optimal conditions. In spite of a narrow working range, the lower detection limit of the immunoassay was about 2 ng mL−1. 相似文献
127.
J. Hanus L Bellier W. Olszewski Th. Sundberg M. Lundborg L. W. Winkler L. Mascarelli A. Blasi A. Panchaud P. Bohrisch F. Kürschner E. Rupp St. Weiser H. G. Donáth W. Arnold O. Köpke W. Manchot K. W. Rosenmund W. Kuhnhenn W. Vaubel H. P. Kaufmann E. Hansen-Schmidt E. Schulek H. Ingle K. H. Bauer P. Manicke W. Fahrion M. Auerbach S. Fachini R. Ehrenstein P. Griegel Y. Toyama 《Analytical and bioanalytical chemistry》1927,72(4):163-173
128.
Naofumi Kozai Shinya Yamasaki Toshihiko Ohnuki 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(3):1581-1587
To elucidate the sorption behaviors of radionuclides in multi-mineral systems and the mutual effects of minerals on this sorption, we carried out the sorption and desorption experiments of neptunium(V) on Na-montmorillonite-based two-mineral phasic systems (montmorillonite–calcite, montmorillonite–apatite). In the montmorillonite–calcite system, the sorption on the montmorillonite moiety decreased with increasing calcite content due to interference by the calcium ions dissolved from the calcite moiety, while no accumulation of Np to the calcite was observed. Total sorption of Np on the montmorillonite–apatite system was larger than that on apatite-free Na-montmorillonite, but the sorption on the montmorillonite moiety in this system was less than that on apatite-free Na-montmorillonite. Under weakly acid and neutral pH conditions, Np accumulated on the apatite moiety in a short period. At final pH 4 or less, though the pH condition was sufficient to dissolve the apatite moiety completely, the sorption very slowly increased with time and the increased Np was unexchangeable with 1 M KCl solution. This increase of the unexchangeable sorption cannot be explained by the knowledge accumulated so far. 相似文献
129.
Ken-ichi Toyama 《Tetrahedron letters》2006,47(40):7163-7166
We have developed a chemoenzymatic synthesis of (R)-thiolactomycin (1) having a chiral quaternary carbon atom at C5. In the kinetic resolution of the thiotetronic acid precursor 4, both enantiomers were obtained with high enantiomeric excess by use of Chirazyme® L-2. Chemical transformations of the (R)-alcohol 4 provided the chiral (R)-thiolactomycin (1) in 36% yield in five steps. 相似文献
130.
Negishi Y Tsunoyama H Suzuki M Kawamura N Matsushita MM Maruyama K Sugawara T Yokoyama T Tsukuda T 《Journal of the American Chemical Society》2006,128(37):12034-12035
We report herein the X-ray magnetic circular dichroism (XMCD) at the Au L2,3 edges of a series of Au clusters protected by glutathione (GSH). The samples used here included AuN(SG)M with (N, M) = (10, 10), (15, 13), (18, 14), (22, 16), (25, 18), (29, 20), (39, 24) and a sodium gold(I) thiomalate (SGT) as a reference. Magnetic moments per cluster were found to be increased with size, whereas those per Au-S bond were nearly constant. This finding suggests that a localized hole created by Au-S bonding at the gold/glutathione interface, rather than the quantum size effect, is responsible for the spin polarization of gold clusters. 相似文献