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91.
Shigeori Takenaka Kenji Iwamasa Makoto Takagi Norikazu Nishino Hisakazu Mihara Tutomu Fujimoto 《Journal of heterocyclic chemistry》1996,33(6):2043-2046
A peptide-intercalator conjugate was synthesized by connecting acridine with a Gln-Gln-Ser-Ile-Glu-Gln-Leu-Glu-Asn sequence representing the DNA recognizing region of 434 phage repressor protein. This conjugate 7 binds to DNA in spite of its anionic character with the aid of the intercalator. 相似文献
92.
Norikazu Ueyama Kazuyuki Takahashi Akira Onoda Takaaki Okamura Hitoshi Yamamoto 《Macromolecular Symposia》2003,204(1):287-294
Biologically important Ca-proteins and Ca-biominerals as metal-polymer complexes are often regulated by the complexation and demetalation with the biopolymers. Metal-oxygen bond is supported by NH···O hydrogen bonds between coordinating oxyanion and neighboring amide NH and by the successive hydrogen bonding networks. Carboxylate anion under hydrophobic conditions has a high basicity that leads to a covalent Ca-O bond character that is significantly affected by the NH···O hydrogen bond. The hydrogen bonds in Asp-containing tripeptide fragments in Ca-proteins presumably control coordination/dissociation of metal-oxygen bonds. Our systematic studies of carboxylate, sulfonate and phosphate Ca(II) complexes demonstrate a relationship between the basicity of oxyanion in carboxylate and hydrogen bonds as cooperating with the oligopeptide conformation in Asp-containing Ca(II) complexes. Hydrogen bonds between carboxylate oxyanion and amide NH, controlled by a conformational switching of oligopeptide fragments, seem to be one of essential factors for the regulatory formation of Ca-proteins and nano-architectures in connection with the interface structure of inorganic and organic phases in biominerals. 相似文献
93.
Yamada M Ichikawa T Yamano T Kikumoto F Nishikimi Y Tamura N Kitazaki T 《Chemical & pharmaceutical bulletin》2006,54(1):58-62
Two new synthetic methods were established for the efficient synthesis of optically active cyclohexene antisepsis agent, ethyl (6R)-6-[N-(2-chloro-4-fluorophenyl)sulfamoyl]cyclohex-1-ene-1-carboxylate [(R)-1: TAK-242)]. The first method involved recrystallization from methanol of the diastereomeric mixture (6RS,1'R)-7, obtained by esterification of carboxylic acid 3 with (S)-1-(4-nitrophenyl)ethanol [(S)-5)] to give the desired isomer (6R,1'R)-7 with 99% de in 32% yield. Subsequent catalytic hydrogenolysis and esterification gave (R)-1 with >99% ee. The second method employed enantioselective hydrolysis of acetoxymethyl ester 9a (prepared by alkylation of 3 with bromomethyl acetate) with Lipase PS-D to give the eutomeric enantiomer (R)-9a with excellent enantioselectivity (>99% ee) and high yield (48%). The desired (R)-1 was then obtained by transesterification with ethanol in the presence of concentrated sulfuric acid without loss of ee. Of these, the procedure employing enzymatic kinetic resolution using Lipase PS-D is the more efficient and practical preparation of (R)-1. 相似文献
94.
Zhu HF Fan J Okamura TA Zhang ZH Liu GX Yu KB Sun WY Ueyama N 《Inorganic chemistry》2006,45(10):3941-3948
Three novel metal-organic architectures, [Ag3(bta)].1.5H2O (1), [Cd3(bta)2(H2O)7].5H2O (2), and [Cu11(bta)6(Hbta)2(H2O)10].29H2O (3), were obtained by reactions of the corresponding metal salts with a flexible tripodal ligand, benzene-1,3,5-triacetic acid (H3bta), and their structures were determined by single-crystal X-ray diffraction studies. The results revealed that, in complexes 1 and 2, the carboxylate groups of the bta3- ligand adopted varied coordination modes to link metal atoms and further to form three-dimensional structures with open channels occupied by water molecules, while in complex 3, for the first time, the flexible H3bta acted as a secondary building unit to generate a novel nanometer-sized metallocage, which is composed of a Cu(II) paddle wheel (square secondary building units) and bta3-/Hbta2- organic links (triangular secondary building units). The photoluminescence properties of complexes 1 and 2 were investigated, and the results showed that 2 exhibited photoluminescence in the solid state at room temperature. 相似文献
95.
96.
[reaction: see text] A novel and efficient procedure for the generation of the reactive indole-2,3-quinodimethane intermediates from the allenylanilines is described. The indole-2,3-quinodimethane intermediates were captured by several dienophiles to afford the corresponding tetrahydro- and dihydrocarbazole derivatives. This method is significantly different from the previously reported ones, which involve the 1,4-elimination or its related reactions of the indole derivatives that possess suitable substituents at both the C-2 and C-3 positions. 相似文献
97.
98.
Yasui T Omoto Y Osato K Kaji N Suzuki N Naito T Watanabe M Okamoto Y Tokeshi M Shamoto E Baba Y 《Lab on a chip》2011,11(19):3356-3360
We developed a new passive-type micromixer based on the baker's transformation and realized a fast mixing of a protein solution, which has lower diffusion constant. The baker's transformation is an ideal mixing method, but there is no report on the microfluidic baker's transformation (MBT), since it is required to fabricate the complicated three-dimensional (3D) structure to realize the MBT device. In this note, we successfully fabricate the MBT device by using precision diamond cutting of an oxygen-free copper substrate for the mould fabrication and PDMS replication. The MBT device with 10.4 mm mixing length enables us to achieve complete mixing of a FITC solution (D = 2.6 × 10(-10) m(2) s(-1)) within 51 ms and an IgG solution (D = 4.6 × 10(-11) m(2) s(-1)) within 306 ms. Its mixing speed is 70-fold higher for a FITC solution and 900-fold higher for an IgG solution than the mixing speed by the microchannel without MBT structures. The Péclet number to attain complete mixing in the MBT device is estimated to be 6.9 × 10(4). 相似文献
99.
100.
Zheng-Hua Zhang Wen-Li Meng Taka-Aki Okamura Ling-Yan Kong Norikazu Ueyama 《Supramolecular chemistry》2013,25(4):317-325
Three metal-organic frameworks (MOFs) [La(bta)(H2O)]n (1), [La(bta)(H2O)2·H2O]n (2) and [Er(bta)(H2O)2·H2O]n (3) with different structures were synthesized by reactions of 1,3,5-benzenetriacetic acid (H3bta) with the corresponding lanthanide salts under different conditions. X-ray diffraction analyses reveal that complexes 1 and 2 have the same metal atom and ligand but different structures. In 1, each bta3 ? adopts cis, cis, cis conformation and acts as a μ6-bridge linking six lanthanum atoms to form a 2D framework; while in 2, the bta3 ? has cis, trans, trans conformation and serves as a μ5-bridging ligand, which results in a 3D channel-like structure. In the case of 3, each bta3 ? also adopts cis, trans, trans conformation but acts as a μ4-bridge linking four erbium atoms to form a 3D channel-like framework. The results imply that the reaction conditions have great impact on the structure of MOFs, and the flexible triacid ligand H3bta is versatile and can adopt different conformations in the formation of MOFs. The magnetic property of complex 3 was investigated in the temperature range of 1.8–300 K. 相似文献