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51.
Okimoto N Nakamura T Suenaga A Futatsugi N Hirano Y Yamaguchi I Ebisuzaki T 《Journal of the American Chemical Society》2004,126(40):13132-13139
Two molecular dynamics (MD) simulations totaling 25 ns of simulation time of monomeric scytalone dehydratase (SD) were performed. The enzyme has a ligand-binding pocket containing a cone-shaped alpha+beta barrel, and the C-terminal region covers the binding pocket. Our simulations clarified the difference in protein dynamics and conformation between the liganded protein and the unliganded protein. The liganded protein held the ligand molecule tightly and the initial structure was maintained during the simulation. The unliganded protein, on the other hand, fluctuated dynamically and its structure changed largely from the initial structure. In the equilibrium state, the binding pocket was fully solvated by opening of the C-terminal region, and the protein dynamics was connected with hydration water molecules entry into and release from the binding pocket. In addition, the cooperative motions of the unliganded protein and the hydration water molecules produced the path through the protein interior for ligand binding. 相似文献
52.
Shin-ichi Hirano Toshinobu Yogo Wataru Sakamoto Seiji Yamada Tomoyuki Nakamura Tomoe Yamammto Hiroyuki Ukai Kouichi Banno Tomoko Nakafuku Yukari Ando 《Journal of Sol-Gel Science and Technology》2003,26(1-3):35-41
Nano sized crystalline particles/polymer hybrids were synthesized form designed metal-organic precursors. The newly developed method is composed of the synthesis of organic matrix by polymerization and the in situ nucleation and growth of crystalline oxide particles in the organic matrix below 100°C. The design of metal-organic precursor modified with polymerizable ligand and the selection of reaction conditions does influence the size and crystallinity of ceramic particles in organic matrix. The nano-sized magnetic particle/polymer hybrid exhibits the interesting feature of superparamagnetism and quantum size effect. The crystalline particles of BaTiO3/, PbTiO3/, and KNbO3/polymer hybrids behave to be dielectric and show the typical electro-rheological behavior. 相似文献
53.
Three-component reactions of aldehydes, ammonia, and allylboronates were found to provide homoallylic primary amines in high yields with high chemo- and stereoselectivities. A two-step, one-pot, stereoselective synthesis of an uncommon alpha-amino acid, alloisoleucine, was achieved utilizing this reaction. 相似文献
54.
Preparation of Gd(2)O(3) : Eu(3+) and Gd(2)O(2)S : Eu(3+) phosphor fine particles using an emulsion liquid membrane system 总被引:3,自引:0,他引:3
Size- (submicrometer-sized) and morphology- (spherical) controlled composite Gd-Eu oxalate particles were prepared in an emulsion liquid membrane (water-in-oil-in-water emulsion) system. The oxalate particles thus prepared were calcined in air to obtain Gd(2)O(3) : Eu(3+) phosphor particles and in sulfur atmosphere to obtain Gd(2)O(2)S : Eu(3+) phosphor particles. These submicrometer-sized spherical phosphor particles showed photoluminescence properties with emission peak at 614 nm for Gd(2)O(3) : Eu(3+) and 628 nm for Gd(2)O(2)S : Eu(3+). 相似文献
55.
Takushi Kurihara Mariko Sugiyama Hiroshi Hirano Ken-Ichi Tomita Masayoshi Sakaki 《Journal of heterocyclic chemistry》1975,12(3):541-545
Reaction of o-nitrobenzylideneacetylacetone ( 1a ) with hydrazine dihydrochloride in methanol gave 4-(α-methoxy-o-nitrobenzyl)-3,5-dimethylpyrazole hydrochloride ( 4a ), whose structure was unambigously confirmed by an X-ray crystallographic analysis, via 4-(o-nitrobenzylidene)-3,5-dimethylisopyrazole ( 2a ). Compound 2a was synthesized by condensation of 1a with hydrazine dihydrochloride in acetonitrile. Analogously the corresponding o-chloro derivatives ( 2b, 4b ) were obtained. These were converted to N-methyl ( 6b ) and N-acetyl ( 7a,b ) derivatives and the behaviors on bromination and pyrolysis were investigated. 相似文献
56.
Gel-based proteomics reveals potential novel protein markers of ozone stress in leaves of cultivated bean and maize species of Panama 总被引:1,自引:0,他引:1
Torres NL Cho K Shibato J Hirano M Kubo A Masuo Y Iwahashi H Jwa NS Agrawal GK Rakwal R 《Electrophoresis》2007,28(23):4369-4381
We examined responses of cultivated bean (Phaseolus vulgaris L. cv. IDIAP R-3) and maize (Zea mays L. cv. Guarare 8128) plants exposed to ozone (O(3)) using a leaf injury assessment and proteomics approach. Plants grown for 16 days in greenhouse were transferred to an O(3) chamber and exposed continuously to 0.2 ppm O(3) or filtered pollutant-free air for up to 72 h. CBB-stained gels revealed changes in ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) protein. By Western analysis changes in marker proteins for O(3) damage in leaves by 1-DE were checked. In bean leaves, two superoxide dismutase (SOD) protein (19 and 20 kDa) were dramatically decreased, while ascorbate peroxidase (APX, 25 kDa), small heat shock protein (HSP, 33 kDa), and a naringenin-7-O-methyltransferase (NOMT, 42 kDa) were increased by O(3). In maize leaves, expression levels of catalase (increased), SOD (decreased), and APX (increased) were drastically changed by O(3) depending on the leaf stage, whereas crossreacting HSPs (24 and 30 kDa) and NOMT (41 kDa) proteins were strongly increased in O(3)-stressed younger leaves. These results indicated a clear modulation of oxidative stress-, heat shock-, and secondary metabolism-related proteins by O(3). Finally, 2-DE at 72 h after O(3) exposure revealed changes (induction/suppression) in expression levels of 25 and 12 protein spots in bean and maize leaves, respectively. Out of these, ten and nine nonredundant proteins in bean and maize, respectively, were identified by MS. A novel pathogenesis-related protein 2 may serve as a potential marker for O(3) stress in bean. 相似文献
57.
Jiang Y Wang Z Xu H Chen H Zhang X Smet M Dehaen W Hirano Y Ozaki Y 《Langmuir : the ACS journal of surfaces and colloids》2006,22(8):3715-3720
This article describes the preparation of pH-responsive self-assembled monolayers (SAMs) of acylated anthranilate-terminated alkanethiol. These monolayers are formed by chemisorption of the alkanethiol molecules onto a gold surface, resulting in different wetting properties of the surfaces depending upon the pH. By using various characterization techniques (e.g., infrared spectroscopy, cyclic voltammetry, contact angle measurements, and surface energy analysis), we have found that the changes in the wetting properties originate from the different surface structures of the monolayers in different pH environments. From surface energy analysis, we found that the disperse components of the surface energy on such SAMs predominate after treatment with pH 1 water, whereas the polar components of the surface energy on such SAMs predominate after treatment with pH 13 water. It is greatly anticipated that this line of research will provide new insight into the mechanism behind pH-responsive properties, facilitating the design and synthesis of new surface-active molecules for the fabrication of pH-responsive functional surfaces. 相似文献
58.
Yuto Sumida Yuko Takada Sayuri Hayashi Koji Hirano Hideki Yorimitsu Dr. Koichiro Oshima Prof. Dr. 《化学:亚洲杂志》2008,3(1):119-125
The treatment of an aldehyde with a tertiary homoallylic alcohol at 100–250 °C in the presence of cesium carbonate and a rhodium catalyst leads to allyl transfer from the homoallylic alcohol to the aldehyde. The process includes Rh‐mediated retroallylation to form an allyl rhodium species as the key intermediate. The homoallylic alcohol formed initially through allyl transfer is converted under the reaction conditions into the corresponding saturated ketone when bulky ligands are used. Microwave heating at 250 °C accelerates the reaction significantly. 相似文献
59.
We have determined that a cationic rhodium(I)/BINAP complex catalyzes a [2+2+2] cycloaddition of 1,6-diynes with a protected dehydroamino acid, leading to protected α-amino acids bearing a quaternary carbon center in high yield with high enantioselectivity. 相似文献
60.
H. C. Zeng T. C. Chong L. C. Lim H. Kumagai M. Hirano 《Journal of Crystal Growth》1996,160(3-4):289-295
The study of meniscus effects on the directional growth of single crystals of potassium niobate (KNbO3) with a [110]pc oriented seed by the top-seeded-solution-growth technique has been described. The directional growth of KNbO3 single crystals has been illustrated for different crystallographic orientations of the crystal. Experimental results show that the shape of the solution flux meniscus, which is determined by a number of growth parameters, has a significant effect on growth rates on different 100pc, 010pc and 001pc type surfaces. Findings based on this work enable one to select a dominant growth direction and hence to engineer the geometrical shaping of resultant KNbO3 single crystals through careful control of growth parameters. Maximum crystal dimensions for the grown KNbO3 along [100]pc and [001]pc achieved in this work are 34.0 and 31.2 mm, respectively. 相似文献