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排序方式: 共有553条查询结果,搜索用时 15 毫秒
51.
Kotaro Nagatani Yunosuke Hoshino Haruka Tezuka Masahisa Nakada 《Tetrahedron letters》2017,58(10):959-962
A synthetic pathway to the C-ring fragment of cotylenin A which emerged from our retrosynthetic analysis of cotylenin A is described. The catalytic asymmetric intramolecular cyclopropanation (CAIMCP) of the α-diazo-β-keto ester bearing 2,4,6-trimethylphenyl group as the ester part has been found to afford the crystalline product with high ee, which allowed to establish the approach to the C-ring fragment which required ten-pot operations. The developed approach would be beneficial to a large scale synthesis of the C-ring fragment for the total synthesis of cotylenin A. 相似文献
52.
Makoto Mouri Taiji Ikawa Mamiko Narita Fumihiko Hoshino Osamu Watanabe 《Macromolecular bioscience》2010,10(6):612-620
In our photo‐induced immobilization technique for an antibody (IgG) using azopolymers, the introduction of COOH and NMe2 into the azopolymers, which can introduce surface charges, strongly affected the immobilization properties such as the efficiency of immobilization and the activity of the immobilized IgG (i.e., the orientation of the immobilized IgG). The introduction of COOH promoted a more active orientation of the immobilized IgG. The orientation was determined during the adsorption process onto the azopolymer surface in solution before photo‐immobilization, and was maintained during the photo‐immobilization. The surface charge of the azopolymer appears to be an important factor for IgG orientation, which involves electrostatic interactions between its Fab and the azopolymer surface.
53.
Eri Sano Weihua Li Hitomi Yuki Xinli Liu Tomomi Furihata Kaoru Kobayashi Kan Chiba Saburo Neya Tyuji Hoshino 《Journal of computational chemistry》2010,31(15):2746-2758
Cytochrome P450 (CYP) is deeply involved in the metabolism of chemicals including pharmaceuticals. Therefore, polymorphisms of this enzyme have been widely studied to avoid unfavorable side effects of drugs in chemotherapy. In this work, we performed computational analysis of the mechanism of the decrease in enzymatic activity for three typical polymorphisms in CYP 2C9 species: *2, *3, and *5. Based on the equilibrated structure obtained by molecular dynamics simulation, the volume of the binding pocket and the fluctuation of amino residues responsible for substrate holding were compared between the wild type and the three variants. Further docking simulation was carried out to evaluate the appropriateness of the binding pocket to accommodate substrate chemicals. Every polymorphic variant was suggested to be inferior to the wild type in enzymatic ability from the structural viewpoint. F‐G helices were obviously displaced outward in CYP2C9*2. Expansion of the binding pocket, especially the space near F′ helix, was remarkable in CYP2C9*3. Disappearance of the hydrogen bond between K helix and β4 loop was observed in CYP2C9*5. The reduction of catalytic activity of those variants can be explained from the deformation of the binding pocket and the consequent change in binding mode of substrate chemicals. The computational approach is effective for predicting the enzymatic activity of polymorphic variants of CYP. This prediction will be helpful for advanced drug design because calculations forecast unexpected change in drug efficacy for individuals. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
54.
A novel type of symmetry breaking is reported for the two-channel Kondo lattice where conduction electrons have spin and orbital (channel) degrees of freedom. Using the continuous-time quantum Monte?Carlo and the dynamical mean-field theory, a spontaneous breaking of the orbital symmetry is observed. The tiny breakdown of orbital occupation number, however, vanishes if the conduction electrons have the particle-hole symmetry. The proper order parameter instead is identified as a composite quantity representing the orbital-selective Kondo effect. The single-particle spectrum of the selected orbital shows insulating property, while the other orbital behaves as a Fermi liquid. This composite order is the first example of odd-frequency order other than off-diagonal order (superconductivity), and is a candidate of hidden order in f-electron systems. 相似文献
55.
We numerically investigate the propagation of light through the photonic crystal (PhC) waveguide on low refraction index material for near-field light focusing at the visible wavelength (635 nm) by incorporating a center air slot and Fabry-Perot resonator on the scanning tip. Perturbations by water and substrate refraction index changes of the PhC are analyzed by the finite-difference time-domain method to show minimal impact on light confinement and throughput. Such a total dielectric probe tip design has great potential to complement the current widely used metal-coated optical-fiber-based light confinement probe. 相似文献
56.
Spectrophotometric determination of titanium(IV) was accomplished with o-carboxyphenylfluorone (OCPF) in the presence of hexadecyltrimethyl ammonium chloride (HTAC) under strongly acidic media. In the determination of titanium(IV), Beer's law was obeyed in the range of 24-340 ng mL−1 with an effective molar absorption coefficient (at 530 nm) and relative standard deviation of 2.24 × 105 dm3 mol−1 cm−1 and 0.64% (n = 8), respectively. The severe interference of iron ions was easily eliminated by the addition of ethylenediaminetetraacetic acid (EDTA); the effects of other foreign substances were low. Equilibrium and kinetic studies under analytical conditions were investigated to quantitatively evaluate the reaction mechanism. The obtained orange complex is considered to be Ti(OCPF)4. Its stability log Kf and rate constant Kobs are 16.88 and 1.65 × 10−2 s−1, respectively. It is suggested that the color of the complex is related to the species of OCPF in the solution. 相似文献
57.
Sato T Yoshida S Hoshino H Tanno M Nakajima M Hoshino T 《Journal of the American Chemical Society》2011,133(25):9734-9737
In this study, mono- and pentacyclic C(35) terpenes from Bacillus subtilis were biosynthesized via the cyclization of C(35) isoprenoid using purified enzymes, including the first identified new terpene cyclase that shows no sequence homology to any of the known terpene cyclases. On the basis of these findings, we propose that these C(35) terpenes should be called the new family of "sesquarterpenes." 相似文献
58.
A laminar boundary-layer heat transfer in a jacketed, stirred tank with non-Newtonian fluids has been experimentally and
theoretically examined. Heat transfer rates from jacket to process liquid through the stirred tank wall were measured for
different large-scale impeller designs and rheological properties. On the basis of the laminar boundary-layer theory, we developed
a theoretical correlation for non-Newtonian laminar tank-side film heat transfer coefficients in stirred tanks. The correlation
was derived using von Karman's integral technique. Satisfactory agreement between the predictions of the proposed correlation
and the present experimental data for viscous Newtonian and non-Newtonian laminar heat transfer in stirred tanks was obtained.
Received on 20 February 2001 / Published online: 29 November 2001 相似文献
59.
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