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61.
We developed a new convenient method for generation of an abasic site at the 3'-terminus of an oligonucleotide. This method uses a 1-deaza-2'-deoxyguanosine residue, which easily undergoes depurination under acidic conditions. The abasic site of the oligonucleotide can be further modified with external functional groups. We report herein the chemical stability of 1-deaza-2'-deoxyguanosine in the oligodeoxynucleotide and the application to the postsynthetic modification of an oligonucleotide by utilizing the chemical property of 1-deaza-2'-deoxyguanosine. [Structure: see text] 相似文献
62.
Kenzo Kitayama Hiroyuki Ohno Masaru Kurahashi Eiko Koizumi Manabu Inagaki 《Journal of solid state chemistry》2003,174(2):249-256
Phase equilibrium was established in the Yb-Mn-O and Dy-Mn-O systems at 1100°C by varying the oxygen partial pressure from −log (PO2/atm)=0-13.00, allowing construction of phase diagrams at 1100°C for the systems Ln2O3-MnO-MnO2. Under experimental conditions, Yb2O3, MnO, Mn3O4, and YbMnO3 phases are found to be present in the Yb-Mn-O system, whereas Dy2O3, MnO, Mn3O4 DyMnO3, and DyMn2O5 phases are present in the Dy-Mn-O system. Ln2MnO4, Mn2O3, and MnO2 are not stable in either system. Small nonstoichiometric ranges are found in the LnMnO3 phase, with the nonstoichiometry represented by the equations, NO/NYbMnO3=1.00×10−4(log PO2)3+1.30×10−3(log PO2)2+7.20×10−3(log PO2)+5.00×10−5 and NO/NDyMnO3=1.00×10−4(log PO2)3+1.80×10−3(log PO2)2+9.30×10−3(log PO2)+1.69×10−2. Activities of the components in the solid solutions are calculated using these equations. LnMnO3 may range Ln2O3-rich to Ln2O3-poor, while MnO is slightly nonstoichiometric to the oxygen-rich side. DyMn2O5 also seems to be nonstoichiometric. Lattice constants of LnMnO3 under different oxygen partial pressures were determined, as well as lattice constants of DyMn2O5 quenched in air. The standard Gibbs energy changes of reactions appearing in the phase diagrams were calculated. 相似文献
63.
Prof. Dr. Seiichi Uchiyama Kayo Yano Eiko Fukatsu Prof. Dr. A. Prasanna de Silva 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(36):8522-8527
One of the challenges for fluorescent sensors is to reduce their target environment size from a micrometer scale, such as biological cells, to a nanometer scale. Proton maps near membranes are of importance in bioenergetics and are the first goal in nanometer-scale analysis with fluorescent sensors. Thirty-three fluorescent photoinduced-electron-transfer pH sensors bearing an environment-sensitive benzofurazan fluorophore and having different hydrophobicity/hydrophilicity and hydrogen-bonding abilities were prepared. These sensors were scattered in nanospaces associated with anionic and cationic micelles as model membranes to indicate proton availability and polarity in local spaces. Gathering the data from the sensors allowed the successful drawing of proton maps near anionic and cationic micelles, in which electrostatic attraction/repulsion of protons by the charged head groups of micelles and dielectric suppression of protons were clearly observed. 相似文献
64.
Eiko Ohtsuka Masahiko Shiraishi Morio Ikehara 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):365-368
Abstract New condensing reagents, arenesulfonyl 5-(pyridin-2-yl)tetrazoles have been synthesized and used for stereospecific synthesis of dinucleoside monophosphate aryl esters. 相似文献
65.
Nobuyasu Itoh Takamitsu Otake Yoshie Aoyagi Mayumi Matsuo Takashi Yarita 《Chromatographia》2009,70(7-8):1073-1078
We applied liquid chromatography-dopant-assisted atmospheric pressure photoionization-mass spectrometry to quantify four distinct pesticides (isoprothiolane, fenitrothion, fthalide, and ethophenprox) in unpolished rice flour. Although the effect of acetone as a dopant on enhancement of ionization differed among the pesticides, the analytical results by LC-DA-APPI-MS with a dopant flow rate of 50 μL min?1 were not only repeatable (relative SD < 9%, n = 3) but also comparable to those by gas chromatography–mass spectrometry. 相似文献
66.
Yuji Suzuki Takanori Niwa Eiko Yasui Megumi Mizukami Masaaki Miyashita Shinji Nagumo 《Tetrahedron letters》2012,53(11):1337-1340
A tandem reaction consisting of five membered-ring selective Prins cyclization and subsequent Friedel–Crafts cyclization was developed. The reactions of phenyl homoallylic alcohol 3 and benzaldehyde derivatives 6 afforded tetrahydroindenofurans 7 or pentacyclic products 8, depending upon the quantity of 6. Also homoallylic alcohol 12 having an alkyne–cobalt moiety reacted with 6 to give rise to tetrahydroindenofurans 13 in good yields. 相似文献
67.
One-electron reduction of kinetically stabilized dipnictenes: synthesis of dipnictene anion radicals
Sasamori T Mieda E Nagahora N Sato K Shiomi D Takui T Hosoi Y Furukawa Y Takagi N Nagase S Tokitoh N 《Journal of the American Chemical Society》2006,128(38):12582-12588
The redox behavior of kinetically stabilized dipnictenes, BbtE=EBbt [E = P, Sb, Bi; Bbt = 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl], was systematically disclosed using cyclic voltammetry and theoretical calculations. It was found that they showed reversible one-electron redox couples in the reduction region. The anion radical species of the Bbt-substituted diphosphene and distibene were successfully synthesized by the reduction of the corresponding neutral dipnictenes (BbtP=PBbt and BbtSb=SbBbt). Their structures were reasonably characterized by ESR, UV-vis, and Raman spectroscopy, and the distibene anion radical was structurally characterized by X-ray crystallographic analysis. 相似文献
68.
We synthesized [2]rotaxanes by the reactions catalyzed by a macrocyclic Cu(I)-phenanthroline complex. The catalytic site was located inside the ring component so that the rotaxane could be selectively formed. A C-S bond-forming reaction and oxidative dimerization of alkyne was utilized for the efficient synthesis of a new series of [2]rotaxanes. [reaction: see text] 相似文献
69.
Matsuya T Otake K Tashiro S Hoshino N Katada M Okuyama T 《Analytical and bioanalytical chemistry》2006,385(5):797-806
We have developed a new time-resolved fluorometric (TRF) microarray detection system consisting of fluorescent NH2 nanosphere, TRF microarray detector and gamma-irradiated polystyrene chip. Using the TRF microarray detector, we detected 500 particles of the fluorescent nanosphere in one channel. Cross-talk fluorescence from the adjacent channels was little observed in the TRF microarray detector (<0.0004 %). The TRF microarray detection system was further applied for serum allergen-specific immunoglobulin E (IgE) multi-analyses. As a labeled tag antibody, an anti-human IgE Fab’ fragment-conjugated fluorescent nanosphere (Fab’ nanosphere) was prepared as described previously. As a chip surface appropriate for allergen immobilization, the polystyrene chip surface was modified by gamma irradiation. The immunoassay reactivity using the gamma-irradiated polystyrene chip was approximately 2.5-times improved compared with that of the non-treated polystyrene chip. Non-specific adsorption of the Fab’ nanosphere onto the gamma-irradiated polystyrene chip surface was very low level (<0.0009 %). In only 20 μl of serum, six allergen-specific IgEs could be simultaneously determined in one reaction well in fewer than 90 min. Good correlation curves were obtained between the microarray immunoassay and the CAP RAST fluoro-enzyme immunoassay (CAP/RAST FEIA) method (r>0.961). Reproducibility (CVs) of the microarray immunoassay was 8.6 % to 19.0 % (n=5). 相似文献
70.
S el-Mekkawy M R Meselhy N Nakamura M Hattori T Kawahata T Otake 《Chemical & pharmaceutical bulletin》1999,47(9):1346-1347
Through bioactivity-guided fractionation, eight phorbol diesters, including five new ones (1-5), were isolated from the seeds of Croton tiglium collected in Egypt. 12-O-Acetylphorbol-13-decanoate (6) and 12-O-decanoylphorbol-13-(2-methylbutyrate) (4) potently inhibited the HIV-1-induced cytopathic effect on MT-4 cells (IC100 values of 7.6 ng/ml and 7.81 micrograms/ml, and CC0 values of 62.5 micrograms/ml and 31.3 micrograms/ml, respectively) without activating protein kinase C. 相似文献