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111.
Tachi Y Aita K Teramae S Tani F Naruta Y Fukuzumi S Itoh S 《Inorganic chemistry》2004,43(15):4558-4560
A dicopper(I) complex supported by a novel asymmetric pentapyridine dinucleating ligand, consisting of tetradentate and tridentate metal-binding sites, has been synthesized and characterized. The dicopper(I) complex reacted with molecular oxygen at a low temperature to give an unprecedented mu-peroxo dicopper(II) complex presumably having a mu-eta1:eta2 binding mode, the spectroscopic features and the reactivity of which have been explored in detail. 相似文献
112.
The amino acid industry has been steadily expanding since monosodium glutamate was first marketed as a flavoring material in 1909. Its production has recently reached almost the 1 billion dollar level. Amino acids are produced by extraction from protein hydrolyzates, by fermentation with the aid of microorganisms, by enzymatic processes, and by chemical synthesis. To obtain natural L-amino acid, chemical synthesis generally requires two additional steps, i.e. optical resolution and racemization of the D isomer. The most important applications of amino acids include the fortification of plant food and feeds by supplementation of the deficient essential amino acid(s). Apart from their uses in the food industry, medical applications of amino acids (nutritional preparations and therapeutic agents) are becoming increasingly important. 相似文献
113.
Kazuo Itoh Masahiko Chikuma Hisashi Tanaka 《Fresenius' Journal of Analytical Chemistry》1988,330(7):600-604
Summary The hydride generation/atomic absorption spectrometry (AAS) with an automated flow system is useful for the routine analysis of selenium in environmental samples. This method is, however, subject to interferences from transition metal ions and other hydride forming ions. The conditions to minimize the interferences were established: the concentration of hydrochloric acid 6 mol/l; the concentration of tetrahydroborate 0.5%. Iron(III) chloride released the depression of selenium signals by metal ions such as copper(II) and bismuth(III). Selenium in several standard reference materials including sediment samples was determined by the present method and by fluorimetry with 2,3-diaminonaphthalene. The results obtained by the two methods agreed with an acceptable precision. This means that hydride generation/AAS offers good precision and accuracy in the determination of selenium in sediment samples as well as DAN fluorimetry. However, the former is much simpler in operation. The method was applied to the determination of selenium in estuarine sediments collected in Nagoya harbor and Ise Bay. The results can be used to assess the pollution state of these places.
Selenbestimmung in Sedimenten durch AAS mit Hydriderzeugung. Eliminierung von Störungen相似文献
114.
Herein we report the production of enantiopure epoxides through biocatalysis using recombinant Escherichia coli cells expressing Rhodococcus sp. ST-10 styrene monooxygenase (SMO) and Leifsonia sp. S749 alcohol dehydrogenase (LSADH) genes are described. Rhodococcus sp. ST-10 SMO catalyzed the epoxidation of various alkenes, including styrene derivatives, vinyl pyridines, and linear alkenes, to give (S)-epoxides. NADH was regenerated by the reduction of NAD+ by LSADH with 2-propanol. The E. coli biocatalyst was used in an aqueous/organic biphasic reaction system and the reaction conditions were optimized. Under the optimized conditions, 170 mM of (S)-styrene oxide was obtained from styrene in the organic phase with excellent enantiomeric excess (99.8%). This biocatalytic process was used to synthesize various (S)-epoxides. 相似文献
115.
Kazuhiro Marumo Manabu Itoh Sungmin Kang Koichi Sakajiri Junji Watanabe 《Liquid crystals》2013,40(2):234-238
Galactose derivatives were explored as chiral dopants, effective for inducing chiral nematic liquid crystal (LC) phases. Galactose bearing O-isopropylidene substituents at the C3 and C4 and butoxybiphenyl substituents at the C2 and C6 positions exhibits a high helical twisting power (HTP) value of ?74.4 μm?1. Such a high HTP value for the galactose derivative is attributed to (1) linkage of the C3 and C4 carbons with the O-isopropylidene substituent, which places the C2 and C6 substitutes in a skew arrangement at a large angle and (2) enhancement of the affinity with the host nematic LCs by incorporating aromatic substituents at the C2 and C6 positions that are similar to those in the host. 相似文献
116.
117.
Abstract Color centers in rutile-structured MgF2 single crystals irradiated at 20K/360K by reactor neutrons are investigated spectroscopically at LNT. Four different types of the F-F vacancy bond in MgF2 are possibly identified to the observed absorption bands as due to the F2 centers; instead of previous assignments, the 300nm band to the F2(D2h), the 325nm band to the F2(C1), the 355nm band to the F2(C2v), and the 400nm band to the F2(C2h) centers. 相似文献
118.
Dual Chemical Modification of a Polytheonamide Mimic: Rational Design and Synthesis of Ion‐Channel‐Forming 48‐mer Peptides with Potent Cytotoxicity
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Atsushi Hayata Dr. Hiroaki Itoh Shoko Matsutaka Prof.Dr. Masayuki Inoue 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3370-3377
Polytheonamide B ( 1 ) is a natural peptide that displays potent cytotoxicity against P388 mouse leukemia cells (IC50=0.098 nm ). Linear 48‐mer 1 is known to form monovalent cation channels on binding to lipid bilayers. We previously developed a fully synthetic route to 1 , and then achieved the design and synthesis of a structurally simplified analogue of 1 , namely, dansylated polytheonamide mimic 2 . Although the synthetically more accessible 2 was found to emulate the channel function of 1 , its cytotoxicity was decreased 120‐fold. Herein, the chemical preparation and biological evaluation of seven analogues 3 – 9 of 2 are reported. Compounds 3 – 9 were modified at their N terminus and/or the side chain of residue 44 of 2 to alter their physicochemical properties. The total synthesis of 3 – 9 was accomplished in a unified fashion by a combination of solid‐phase and solution‐phase chemistry. Systematic evaluation of the hydrophobicities, single‐channel currents, ion‐exchange activities, and cytotoxicities of 3 – 9 revealed that their hydrophobicities are correlated with the total magnitude of ion exchange and determine their cytotoxic potency. Consequently, the most hydrophobic analogue 9 exhibited the lowest IC50 value, which is comparable to that of 1 . Therefore, these results clarified that the bioactivity of the polytheonamide‐based peptides can be rationally controlled by changing their hydrophobicity at the N and C termini of the 48‐amino‐acid sequence. 相似文献
119.
Pd‐initiated polymerization of diazo compounds bearing dialkoxyphosphinyl group and hydrolysis of the resulting polymers and oligomers to afford phosphonic acid‐containing products
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Hiroaki Shimomoto Akira Oda Motoki Kanayama Tomoya Sako Tomomichi Itoh Eiji Ihara Naohiro Hoshikawa Akihiko Koiwai Naoki Hasegawa 《Journal of polymer science. Part A, Polymer chemistry》2016,54(12):1742-1751
Pd‐initiated polymerization and oligomerization of diazo compounds containing a dialkoxyphosphinyl group are described. Polymerization of 2‐dialkoxyphosphinylethyl diazoacetates with π‐allylPdCl‐based initiating systems afforded C? C main chain polymers bearing phosphonate on each main chain carbon atom. The quantitative transformation of the side chain phosphonate to phosphonic acid resulted in the formation of water soluble polymers having the acid groups accumulated around their main chains, although the carbonyl ester linkage in the side chain was cleaved via intramolecular acid‐assisted hydrolysis in water at 80 °C. Pd‐initiated oligomerization of diethyl diazomethylphosphonate yielded an oligomeric product bearing diethoxyphosphiny groups directly attached to its main chain carbons, with unexpected incorporation of azo group in the main chain framework. Hydrolysis of the phosphonate of the oligomer afforded a water‐soluble product, which was revealed to show higher proton conductivity than poly(vinylphosphonic acid) under certain conditions. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1742–1751 相似文献
120.
Chihiro Manri Takahide Yokoi Hirokazu Nishida 《Applied biochemistry and biotechnology》2017,182(2):609-623
Extracellular vesicles (EV), typified by exosomes or microvesicles, are expected to be effective diagnostic markers for cancers. The sizes of the vesicles range from 20 to 1000 nm, but the size-dependent variations of the contents of EVs are still poorly understood. We succeeded in the size-selective harvesting of the vesicles by utilizing the molecular weight-dependent characteristics of a variety of polyethylene glycols (PEG) as precipitating reagents and analyzed the antigens displayed on the surfaces of the vesicles and the miRNAs included in the vesicles from each size group. As a result, the relatively larger (<100 nm) particles precipitated by PEG5k clearly exhibited the greatest amount of epithelial cell adhesion molecule (EpCAM), from both breast cancer (MCF-7) and colon cancer (HCT116) cells, and a larger quantity of microRNA (miRNA) specific to breast cancer cells (miRNA155 for MCF-7) seemed to be contained in the PEG-precipitated particles. The results demonstrated that the quantities of both the tumor-specific miRNA and protein were similarly distributed among the several classes of the size-sorted EVs and that the size-selective harvesting of EVs may be informative for strategic analyses towards the diagnoses of cancers. 相似文献