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561.
Usui T Nagumo Y Watanabe A Kubota T Komatsu K Kobayashi J Osada H 《Chemistry & biology》2006,13(11):1153-1160
Lymphocytes in T cell activation require extracellular nutrients to provide energy for cellular proliferation and effector functions. Therefore, inhibitors of nutrient transporters are expected to be a new class of immunosuppressant. Here, we report that the molecular target of brasilicardin A (BraA), an immunosuppressive compound, is the amino acid transporter system L. BraA inhibited the cell-cycle progression of murine T cell lymphocyte CTLL-2 cells in G1 phase, and potently inhibited the uptake of amino acids that are substrates for amino acid transport system L. Moreover, BraA stimulated the GCN2 activation and, subsequently, the phosphorylation of eIF2alpha. These results suggest that the immunosuppressive activity of BraA is induced by amino acid deprivation via the inhibition of system L and that the amino acid transporter is a target for immunosuppressant. 相似文献
562.
The reaction coordinate of the S(1)-S(0) internal conversion of azulene has been analyzed using ab initio complete active space self-consistent field method. The stable geometry in S(0) (S(0) geometry) takes a bond-equalized structure where all the peripheral skeletal bond distances are similar to an aromatic CC bond distance. The transannular bond is similar to a normal C-C single bond. The first event upon electronic excitation into S(1) at S(0) geometry is characterized by the following two simultaneous changes in the skeletal bonds; the transannular bond in S(1) increases its double bond character and the aromaticity of the peripheral bonds disappears. In consequence, the most stable azulene in S(1) (S(1) geometry) has a biradical character. To reach the conical intersection between S(1) and S(0) (S(1)S(0)-CIX) where radiationless relaxation takes place, the seven-membered ring greatly deviates from a planar structure. After a transition into S(0) at S(1)S(0)-CIX, the bond-equalized structure is recovered immediately and then the nonplanarity decreases so that azulene again takes the stable planar S(0) geometry. In order to deepen the understanding of the S(1)-S(0) internal conversion, the dipole moments along the reaction coordinate have been analyzed. 相似文献
563.
Eileen Hao Yu Yoko Himuro Madoka Takai Kazuhiko Ishihara 《Applied biochemistry and biotechnology》2010,160(4):1094-1101
In this study, the feasibility of introducing redox property to an amphiphilic phospholipid polymer (PMBN) was investigated.
The active ester group in the side chain of the polymer was used to react with pyrroloquinoline quinine (PQQ). Redox peaks
that corresponded to PQQ redox potentials were observed after the modification. Glucose oxidase was immobilized to the modified
polymer. Electrochemical oxidation of glucose was carried out with the polymer electrode. The oxidation current increased
with elevating glucose concentration indicating electron transfer established between the electrode and enzyme. It suggests
that by modification, PMBN is possible to use for enzyme electrode for bioelectronics. 相似文献
564.
We have discovered that an Ir‐23Nb binary alloy more effectively oxidizes hydrogen peroxide than Ir, Ir‐13Nb, Ir‐17Nb, Ir‐30Nb, Ir‐43Nb, Ir‐62Nb, or Nb. The oxidation capability was determined via cyclic voltammogram measurements of pH‐buffer and hydrogen peroxide. We ascertained that applying a 0.7 V potential produces hydrogen peroxide currents of 9.2 μA/mm2 Ir‐23Nb, 5.3 μA/mm2 Ir, 5.1 μA/mm2 Ir‐17Nb, 3.7 μA/mm2 Ir‐13Nb, 2.0 μA/mm2 Ir‐30Nb, 1.5 μA/mm2 Ir‐43Nb, 0.6 μA/mm2 Ir‐62Nb, and 0.13 μA/mm2 Nb. These results indicate that the effective oxidation of Ir‐23Nb for hydrogen peroxide might be due to its fcc+L12 two‐phase structure and that Ir‐23Nb can be used as an amperometric transducer material. 相似文献
565.
Stefan Feil Greg K. Koyanagi Diethard K. Bohme 《International journal of mass spectrometry》2009,280(1-3):38
Room temperature rate coefficients and product distributions are reported for the reactions initiated in D2O with dications of the alkaline-earth metals Mg, Ca, Sr and Ba. The measurements were performed with a selected-ion flow tube (SIFT) tandem mass spectrometer and electrospray ionization (ESI). Mg2+ reacts with water by a fast electron transfer leading to charge separation with a rate coefficient of 1.4 × 10−9 cm3 molecule−1 s−1. Ca2+ reacts with D2O in a first step to form the adduct Ca2+(D2O), with an effective bimolecular rate coefficient of 2.3 × 10−11 cm3 molecule−1 s−1, which then undergoes rapid charge separation by deuteron transfer to form CaOD+ and D3O+ in a second step with k = 7.9 × 10−10 cm3 molecule−1 s−1. The CaOD+ ion reacts further by clustering up to five more D2O molecules. Sr2+ clusters up to eight D2O molecules and Ba2+ up to seven D2O molecules, with the first addition of D2O being rate determining in each case and the last addition being distinctly slower, as might be expected from a transition in the occupation of the added water molecules from an inner to an outer hydration shell. 相似文献
566.
Itaru Okamoto Dr. Kenji Iwamoto Yuko Watanabe Yoko Miyake Dr. Akira Ono Dr. 《Angewandte Chemie (International ed. in English)》2009,48(9):1648-1651
DNA duplexes containing 5‐modified uracil pairs (5‐bromo, 5‐fluoro, and 5‐cyanouracil) bind selectivity to metal ions. Their selectivity is sensitive to the pH value of the solution (see picture), as the acidities of the modified uracil bases vary according to the electron‐withdrawing properties of the substituents.
567.
A simple interferometric polarimeter with an integrated calibration scheme is proposed for accurate and fast mapping of the state of polarization (SOP). Conventional single-shot polarimeters that detect the amplitude and phase of orthogonally polarized field components by interferometry using Fourier fringe analysis suffers from errors caused by the imperfect reference beam and ambiguity in the spatial carrier frequency in the fringe pattern. In the proposed system, the integrated calibration scheme eliminates those error sources and enables accurate measurement of SOP without prior knowledge of the reference beam and the spatial carrier frequency. 相似文献
568.
激光熔蚀-电感耦合等离子体质谱法测定底泥沉积物中的总汞 总被引:1,自引:0,他引:1
采用激光熔蚀-电感耦合等离子体质谱法(LA-ICP-MS)测定了底泥沉积物中的总汞,沉积物样品经高压压坯后直接进行激光熔蚀测定,并对内标选定、样品粒度以及汞的形态等影响因素进行了研究,以2个底泥标准样和1个土壤标准样的测定结果来绘制标准曲线,并用于实际样品的测定,方法简便实用,测定结果与同位素稀释冷蒸气发生ICP-MS法十分吻合,方法检出限为0.02 mg·kg-1,测定速度可达每小时10样。 相似文献
569.
It was shown that the color property of the recognized visual space of illumination, RVSI was controlled by changing the initial visual information by arranging objects in the room all shifting toward orange direction. We constructed two miniature rooms, D and I, both illuminated by the same daylight type fluorescent lamps but arranged with furniture of different color, those in room I shifting toward color as if they were illuminated by an incandescent lamp. Subjects felt as if room I were illuminated by an incandescent lamp. A test patch was placed midair in each room and its color was judged. When the test patches were placed in room I their colors were all perceived to be shifted toward greenish blue compared to those of test patches placed in room D, in spite of having the same illumination. The results imply that the apparent color of an object is determined not by its chromaticity, but in relation to the color property of the RVSI of the room where the object is observed. 相似文献
570.
Masayuki Ogawa Jyunichi Koyanagi Katsuya Sakuma Akira Tanaka Katsumi Yamamoto 《Journal of heterocyclic chemistry》1999,36(3):819-822
The reaction of methyl 5-(2-isocyanatophenylthio)-2-furancarboxylate 2 with N-methylpiperazine gave 5-(2-N-piperazinocarbamoylphenylthio)-2-furancarboxylate 3a . Furthermore, 4-N-methylpiperazinyl-2-methoxycarbonylfuro[2,3-b][1,5]benzothiazepine 4a was obtained by the Bischler-Napieralski reaction of 3a with phosphorus oxychloride in the present of phosphorus pentoxide. Three furobenzothiazepines could be obtained using the same method. Based on the pharmacological studies of these compounds, it was found that 4-morpholinyl-2-methoxycarbonylfuro[2,3-b][1,5]benzothiazepine 4b had anti-inflammatory activity similar to flufenamic acid. 相似文献