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221.
222.
Numata M Sugiyasu K Kishida T Haraguchi S Fujita N Park SM Yun YJ Kim BH Shinkai S 《Organic & biomolecular chemistry》2008,6(4):712-718
The influence of added polynucleotide on the gelation ability of nucleobase-appended organogelators was investigated. Uracil-appended cholesterol gelator formed a stable organogel in polar organic solvents such as n-butanol. It was found that the addition of the complementary polyadenylic acid (poly(A)) not only stabilizes the gel but also creates the helical structure in the original gel phase. Thymidine and thymine-appended gelators can form stable gel in apolar solvents, such as benzene, where poly(A)-lipid complex can act as a complementary template for the gelator molecules to create the fibrous composites. Based on these findings, we can conclude that self-assembling modes and gelation properties of nucleobase-appended organogelators are controllable by the addition of their complementary polynucleotide in organic solvents. We believe, therefore, that the present system can open the new paths to accelerate development of well-controlled one-dimensional molecular assembly systems, which would be indispensable for the creation of novel nanomaterials based on organic compounds. 相似文献
223.
Metal ion induced allosteric transition in the catalytic activity of an artificial phosphodiesterase
An artificial phosphodiesterase () bearing two types of metal binding sites, a catalytic site and a regulatory bipyridine site showed a unique allosteric transition in the catalytic activity against the metal concentration. The rate constants for the hydrolysis reaction of 2-hydroxypropyl-p-nitrophenyl phosphate (HPNP) and RNA dimer (ApA) with and without an effector metal ion were evaluated; the k(obs) value of HPNP hydrolysis for .(Zn(2+))(3) (2.0 x 10(-4) s(-1)) is 3.3 times larger than that for .(Zn(2+))(2). In the case of and Cu(2+), a 19.4 times larger k(obs) value was obtained for .(Cu(2+))(3) (1.2 x 10(-3) s(-1)) against .(Cu(2+))(2). The increase in the catalytic activity is ascribed to the allosteric conformational transition of induced by the coordination of effector metal ion to the Bpy moiety. A detailed investigation revealed that a conformational change of induced by the third M(2+) complexation enhances the rate of hydrolysis rather than a change in the substrate affinity. 相似文献
224.
Liu S Shinkai N Kakubari I Saitoh H Noguchi K Saitoh T Yamauchi H 《Biomedical chromatography : BMC》2008,22(12):1442-1449
We have established a robust, fully automated analytical method for the analysis of fluvoxamine in rat plasma using a column-switching ion-pair high-performance chromatography system. The plasma sample was injected onto a precolumn packed with Shim-pack MAYI-ODS (50 microm), where the drug was automatically purified and enriched by on-line solid-phase extraction. After elution of the plasma proteins, the analyte was back-flushed from the precolumn and then separated isocratically on a reversed-phase C18 column (L-column ODS) with a mobile phase (acetonitrile-0.1% phosphoric acid, 36:64, v/v) containing 2 mM sodium 1-octanesulfonate. The analyte was monitored by a UV detector at a wavelength of 254 nm. The calibration line for fluvoxamine showed good linearity in the range of 5-5000 ng/mL (r > 0.999) with the limit of quantification of 5 ng/mL (RSD = 6.51%). Accuracy ranged from -2.94 to 4.82%, and the within- and between-day precision of the assay was better than 8% across the calibration range. The analytical sensitivity and accuracy of this assay is suitable for characterization of the pharmacokinetics of orally-administered fluvoxamine in rats. 相似文献
225.
226.
S. Shinkai G. G. Longinescu I. I. Prundeanu G. Gorbach M. Kostic und G. Embden 《Fresenius' Journal of Analytical Chemistry》1940,120(3-4):94-95
Ohne Zusammenfassung 相似文献
227.
S. Shinkai 《Fresenius' Journal of Analytical Chemistry》1940,119(1-2):62
Ohne Zusammenfassung 相似文献
228.
Victoria Mae Tsuruzaki Shinkai Izana Marize Oliveira Sampaio Eline Gomes dos Santos Adan Jesús Galu-Parra Dionisia Pelaes Ferreira Drielly Dayanne Monteiro Santos Baliza Neidiane Farias Ramos Raphael Sanzio Pimenta Rommel Mario Rodriguez Burbano Chubert Bernardo Castro Sena Barbarella Matos Macchi Irlon Maciel Ferreira Edilene Oliveira Silva Jos Luiz Martins do Nascimento 《Molecules (Basel, Switzerland)》2022,27(24)
229.
Masaru Kawaguchi Atsushi Ikeda Seiji Shinkai Ion Neda 《Journal of inclusion phenomena and macrocyclic chemistry》2000,37(1-4):253-258
[60]Fullerene (C60)-calix[n]areneinteractions were studied in toluene:MeCN = 10:1 (v/v)using an electrochemical method. In the presence ofhomooxacalix[3]arenes and calix[5]arenes, bothEpc and pa shifted to the negativepotential, whereas they were scarcely affected by theaddition of calix[4]arenes. The2values electrochemically determined forthe association with C60
- are generallysmaller than the 1 valuesspectroscopically determined for the association withC60. The tendency indicates that thecharge-transfer-type interaction is one of thedriving forces for C60 inclusion.thanks|Author for correspondence 相似文献
230.
Creation of Circularly Polarized Luminescence from an Achiral Polyfluorene Derivative through Complexation with Helix‐Forming Polysaccharides: Importance of the meta‐Linkage Chain for Helix Formation 下载免费PDF全文
Dr. Tomohiro Shiraki Dr. Youichi Tsuchiya Dr. Takao Noguchi Prof. Shun‐ichi Tamaru Nozomu Suzuki Makoto Taguchi Prof. Michiya Fujiki Prof. Seiji Shinkai 《化学:亚洲杂志》2014,9(1):218-222
A circularly polarized luminescence (CPL) material has been created by polymer–polymer complexation between a helix‐forming polysaccharide, schizophyllan (SPG), and a meta‐phenylene‐linked polyfluorene derivative (mPFS). Computational modeling revealed that mPFS can adopt a helical structure although a conventional polyfluorene derivative with a para‐phenylene linkage tends to enjoy a rigid rodlike conformation. Our detailed experimental examination showed that mPFS forms a chiral nanowire complex through cohelix formation with SPG. We have found, as expected, that this cohelical complex emits highly efficient CPL even in an aqueous solution. The appearance of the high CPL property is due to 1) a high quantum yield of the fluorene unit and 2) immobilization of the helically twisted conformation of mPFS in an isolated manner through cohelix formation with SPG. One can propose, therefore, that the SPG/mPFS complex acts as a new high‐performance CPL material with a solvent‐dispersible nanowire structure. 相似文献