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11.
Hashizaki K Taguchi H Itoh C Sakai H Abe M Saito Y Ogawa N 《Chemical & pharmaceutical bulletin》2005,53(1):27-31
Poly(ethylene glycol)-grafted liposomes (PEG-liposomes) were prepared from dipalmitoylphosphatidylcholine (DPPC) with various amounts of distearoyl-N-monomethoxy poly(ethylene glycol)-succinyl-phosphatidylethanolamines (DSPE-PEG) with PEG molecular weights of 1000, 2000, 3000 and 5000. The effects of DSPE-PEG concentration on the permeability of PEG-liposomes were investigated using carboxyfluorescein (CF). In the gel state, the CF leakage from PEG-liposomes was decreased with increasing mole fractions of DSPE-PEG for all PEG molecular weights. In the liquid-crystalline state, the CF leakage from PEG-liposomes containing DSPE-PEG1000 gradually increased with increasing mole fractions of DSPE-PEG, while that of PEG-liposomes whose molecular weight in PEG units was above 2000 rapidly decreased by the addition of DSPE-PEG. Furthermore, no effect of PEG molecular weight on CF leakage was observed. The relationship between the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) (or 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH)) and the mole fraction of DSPE-PEG for PEG-liposomes was also investigated. No significant changes in fluorescence polarization of DPH for liposomal bilayer membranes was observed in the gel and liquid-crystalline states due to the addition of DSPE-PEG, while that of TMA-DPH was decreased compared with that of liposomes without DSPE-PEG in both states. 相似文献
12.
Ken-ichi Fujita Shigeru HashimotoAkihiro Oishi Yoichi Taguchi 《Tetrahedron letters》2003,44(19):3793-3795
After immobilizing arylselenenyl bromide on polymer resin, the oxyselenenylation reaction of olefin was carried out in water. An amphiphilic polymer-supported arylselenenyl bromide was employed, and various intramolecular oxyselenenylation and deselenenylation reactions proceeded smoothly in water in fair chemical yields (up to an 83% yield). 相似文献
13.
S. Kulprecha T. Nihira C. Shimomura K. Yamada N. Nilubol T. Yoshida H. Taguchi 《Tetrahedron》1984,40(15):2843-2846
The microbiological transformation of lithocholic acid (3α-hydroxy-5β-cholanic acid) into 3α, 15β-dihydroxy-5β-cholanic acid by Cunninghamella sp. is Investigated. The structure has been determined on the basis of two-dimensional 1H-NMR. 相似文献
14.
Koga T Taguchi K Kinoshita T Higuchi M 《Chemical communications (Cambridge, England)》2002,(3):242-243
A novel artificial protein with simple primary structure, poly(gamma-methyl-L-glutamate)-grafted polyallylamine, has been prepared and the resultant peptide has shown a unique property of pH-regulated conformation and morphology. 相似文献
15.
Silaned glass beads are applied to the preconcentration and spectrophotometric determination of phosphorus as the phosphomolybdenum blue complex. Traces of phosphorus in water are collected as a phosphomolybdenum blue complex on a column of the beads. The phosphomolybdenum blue is eluted with N,N-dimethylformamide and the absorbance of the eluate continuously monitored at 700 nm. The height of the very sharp peak obtained is proportional to the amount of phosphorus present and 0.1-0.5 mug of phosphorus in a 10-ml sample can be determined reproducibly. Interference from arsenate is eliminated by addition of a reducing agent. High concentrations of silica cause a small positive error. This method is applicable to the analysis of river water and sea-water samples. 相似文献
16.
The effects of the phenyl substituent on the dimerization of copper(II) carboxylate in the solvent extraction of copper(II) with phenylacetic acid using benzene and 1-octanol as a solvent were investigated, at 25 degrees and at the aqueous ionic strength of 0.1M (NaClO(4)). The dimerization of copper(II) phenylacetate has been found to be written as: 2CuA(2)Cu(2)A(4) in 1-octanol, and 2CuA(2)(HA)(2)Cu(2)A(4)(HA)(2) + (HA)(2) in benzene, with the dimerization constants, log K = 2.24 and log K = 4.19, respectively. It was proved that the phenyl group inhibits the formation of the dimeric copper(II) phenylacetate, and its effect is partially shielded by a methylene substituent. 相似文献
17.
Copper mediated alkyl-transfer reaction of trialkylaluminum (R3Al) with (E)-4,4-difluoro-5-hydroxyallylic alcohol derivative smoothly proceeded to give the corresponding 2-alkylated 4-fluoro-5-hydroxyhomoallylic alcohol derivative with completely Z and 2,5-syn selective manner. Regio- and stereoselective conversion of the C5-hydroxyl group of the fluoroolefin thus obtained to amino group could be achieved through one-pot mesylation and azidation reaction. 相似文献
18.
Makoto OzawaTakaaki Taguchi Takayuki ItohYutaka Ebizuka Kevin I Booker-MilburnG.Richard Stephenson Koji Ichinose 《Tetrahedron》2003,59(44):8793-8798
A novel shunt product was isolated from a disruptant of the actVI-ORFA gene involved in the biosynthesis of actinorhodin (ACT) in Streptomyces coelicolor A3(2). Its structure was elucidated as 1,4-naphthoquinone-8-hydroxy-3-[3(S)-acetoxy-butyric acid], (S)-NHAB, based on NMR, MS, and CD spectroscopic data as well as a single crystal X-ray crystallographic analysis. The formation of (S)-NHAB involves a retro-Claisen type C-C bond cleavage of an ACT biosynthetic intermediate. Feeding experiments with [1-13C] and [2-13C] acetates indicated its biosynthetic origin as a single octaketide chain. The relevant gene product, Act-ORFA, which is a functionally unknown protein, is proposed to play a regulatory role related to the multi-enzymatic steps to ACT production, based on the metabolic profile of its disruptant and the wide distribution of actVI-ORFA homologues in the gene clusters for Streptomyces aromatic polyketides. 相似文献
19.
In the presence of CuCN, reaction of γ,γ-dialkoxyallylic zirconium species 1 with imines proceeded at the γ-position of 1 to give gem-dialkoxyhomoallylic amines 3 in high yield. In this reaction, γ,γ-dialkoxyallylic zirconium species 1 acts as an α,β-unsaturated acyl anion equivalent. 相似文献
20.
H Kawai F Sakamoto M Taguchi M Kitamura M Sotomura G Tsukamoto 《Chemical & pharmaceutical bulletin》1991,39(6):1422-1425
Various 4-arylthiomethyl-2-oxo-1,3-dioxole derivatives IIIa-o were synthesized. Their hydrolysis rates by arylesterase (EC 3.1.1.2) and cholinesterase (EC 3.1.1.8) in human serum were evaluated. Some of them were not hydrolyzed by cholinesterase, but were hydrolyzed easily by arylesterase. Among the substrates, sodium 4-((5-methyl-2-oxo-1,3-dioxol-4-yl)methylthio)benzenesulfonate (IIIg) was selected for its substrate reactivity toward arylesterase and its good water solubility. In addition, neither aliesterase (EC 3.1.1.1), acetylesterase (EC 3.1.1.6) nor cholesterol esterase (EC 3.1.1.13) hydrolyzed the compound. IIIg is thus concluded to be a specific substrate for arylesterase. Our assay system for serum arylesterase using IIIg can be readily applied to an automatic analyzer in the diagnosis of liver cirrhosis. 相似文献