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61.
Lee JS Kim DH Liu KH Oh TK Lee CH 《Rapid communications in mass spectrometry : RCM》2005,19(23):3539-3548
Searchable MS/MS spectra libraries, constructed using the results of liquid chromatography coupled with electrospray ionization (ESI) tandem mass spectrometry (LC/MS/MS) with data-dependent acquisition on an ion trap mass spectrometer, are presented with regard to the identification and confirmation of a variety of closely related flavonoids in a set of biological samples. Flavonoids were found to exhibit a maximum amount of structurally specific MS/MS spectra at 45% of normalized collision energy on the instrument used, without wideband activation. These MS/MS spectra were then searched automatically against a 297-substance MS/MS library that contains many previously acquired spectra of standard flavonoids. The possible applications of this powerful technique to biological samples are also discussed. Daidzein and genistein were identified through the MS/MS spectra library while searching through LC/MS/MS data for plant and microbial extracts. Moreover, these compounds proved completely distinguishable from other flavonoids of closely related structures in the MS/MS spectra library, using the NIST MS search program. The applicability of the library-searchable spectra at low concentrations was demonstrated by successful identification of daidzein and genistein at 0.05 and 0.5 microg/mL, respectively. 相似文献
62.
Joo J Kwon SG Yu T Cho M Lee J Yoon J Hyeon T 《The journal of physical chemistry. B》2005,109(32):15297-15302
A simple method of synthesizing a large quantity of TiO(2) nanorods was developed. A nonhydrolytic sol-gel reaction between titanium(IV) isopropoxide and oleic acid at 270 degrees C generated 3.4 nm (diameter) x 38 nm (length) sized TiO(2) nanocrystals. The transmission electron microscopic image showed that the particles have a uniform diameter distribution. X-ray diffraction and selected-area electron diffraction patterns combined with high-resolution transmission electron microscopic image showed that the TiO(2) nanorods are highly crystalline anatase crystal structure grown along the [001] direction. The diameters of the TiO(2) nanorods were controlled by adding 1-hexadecylamine to the reaction mixture as a cosurfactant. TiO(2) nanorods with average sizes of 2.7 nm x 28 nm, 2.2 nm x 32 nm, and 2.0 nm x 39 nm were obtained using 1, 5, and 10 mmol of 1-hexadecylamine, respectively. The optical absorption spectrum of the TiO(2) nanorods exhibited that the band gap of the nanorods was 3.33 eV at room temperature, which is 130 meV larger than that of bulk anatase (3.2 eV), demonstrating the quantum confinement effect. Oleic acid coordinated on the nanorod surface was removed by the reduction of the carboxyl group of oleic acid, and the Brunauer-Emmett-Teller surface area of the resulting naked TiO(2) nanorods was 198 m(2)/g. The naked TiO(2) nanorods exhibited higher photocatalytic activity than the P-25 photocatalyst for the photocatalytic inactivation of E. coli. 相似文献
63.
64.
GITR (glucocorticoid-induced TNF receptor) is a recently identified member of the TNF receptor superfamily. The receptor is preferentially expressed on CD4(+)CD25(+) regulatory T cells and GITR signals break the suppressive activity of the subset. In this study, we wanted to reveal the in vivo function of GITR in herpes simplex virus type 1 (HSV-1) infection. A single injection of anti-GITR mAb (DTA-1) immediately after viral infection significantly increased the number of CD4(+) and CD8(+) T cells expressing CD25, an activation surface marker, and secreting IFN-gamma. We confirmed these in vivo observations by showing ex vivo that re-stimulation of CD4(+) or CD8(+) T cells with a CD4(+) or CD8(+) T-cell-specific HSV-1 peptide, respectively, induced a significant elevation in cell proliferation and in IFN-gamma secretion. Our results indicate that GITR signals play a critical role in the T-cell immunity to HSV-1. 相似文献
65.
Kwon YU Soucy RL Snyder DA Seeberger PH 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(8):2493-2504
We report an efficient and convergent synthesis of a series of oligosaccharides comprised of the malaria GPI glycan (2a), a promising anti-malaria vaccine candidate currently in preclinical trials and several related oligosaccharide sequences (3-8) that are possible biosynthetic precursors of the malarial GPI. A flexible synthetic strategy is disclosed that relies on a late-stage coupling between oligomannosides of varying length and pseudo-disaccharide glycosyl acceptor 11 to readily access various malarial GPI structures. Phosphorylation was accomplished by mild and efficient H-phosphonate chemistry before the final deprotection was carried out by using sodium in ammonia. The direct connection of a thiol group via a phosphate diester linkage to the inositol moiety provides a handle for easy conjugation of the GPI glycan to carrier proteins, immobilization on carbohydrate microarrays and photo-affinity labels identification. These synthetic oligosaccharides will serve as molecular probes. 相似文献
66.
Oh JY Moon JH Lee YH Hyung SW Lee SW Kim MS 《Rapid communications in mass spectrometry : RCM》2005,19(10):1283-1288
Photodissociation (PD) tandem mass spectra have been obtained at 266 nm for the protonated molecules of a tryptic peptide, ASHLGLAR, and of its phenyl isothiocyanate and 4-sulfophenyl isothiocyanate derivatives, generated by matrix-assisted laser desorption/ionization. Derivatization with the aromatic chromophores greatly reduced the intensity of the laser required for efficient PD. Major fragment ions observed in the three spectra are quite similar. General features of the PD tandem mass spectra and their potential utility for analytical purposes are discussed. 相似文献
67.
Nam W Oh SY Sun YJ Kim J Kim WK Woo SK Shin W 《The Journal of organic chemistry》2003,68(20):7903-7906
The catalytic epoxidation of cyclohexene by iron(III) porphyrin complexes and H2O2 has been investigated in alcohol solvents to understand factors affecting the catalyst activity in protic solvents. The yields of cyclohexene oxide and the Fe(III/II) reduction potentials of iron porphyrin complexes were significantly affected by the protic solvents, and there was a close correlation between the product yields and the reduction potentials of the iron porphyrin catalysts. The role of alcohol solvents was proposed to control the electronic nature of iron porphyrin complexes that determines the catalyst activity in the epoxidation of olefins by H2O2. We have also demonstrated that an electron-deficient iron porphyrin complex can catalyze the epoxidation of olefins by H2O2 under conditions of limiting substrate with high conversion efficiency in a solvent mixture of CH3OH and CH2Cl2. 相似文献
68.
Jeon JH Cho SY Kim CW Shin DM Kwon JC Choi KH Kim IG 《Experimental & molecular medicine》2002,34(6):496-499
Human papillomavirus E7 (HPV E7) is a viral oncoprotein that plays an important role in cervical carcinogenesis through binding with retinoblastoma protein (Rb). Inactivation of Rb by E7 is necessary but not sufficient for cellular transformation, suggesting other protein-protein interactions are required for E7-mediated cellular transformation aside from the interaction with Rb. However, studies on the oncogenic function of HPV E7 have been limited by its poor immunoreactivity. In this report, we show that the fixation of purified recombinant HPV E7 on blotted nitrocellulose membrane with glutaldehyde markedly enhanced the immunoreactivity of HPV E7 protein. Using HeLa and Caski cell lines which are infected with HPV 18 and HPV 16, respectively, we demonstrated that native HPV E7 proteins also could be detected by this method. These results therefore can provide the experimental conditions for detection of HPV E7 proteins with greater sensitivity and may help to analyze E7 functions. 相似文献
69.
Kwon M Jeong S Lee KH Park YK Yu J 《Journal of the American Chemical Society》2002,124(47):13996-13997
Our approach to multivalent peptide construction relies on tentacle peptides, also known as a multiple antigenic peptides, which contain two and four repeats of a selected peptide. In this communication, we report the results of preliminary studies aimed at (1) the selection of short peptides against the carbohydrate, sLeX, (2) the synthesis of tentacle dimers and tetramers of the selected peptides, and (3) the determination of affinities and specificities of the peptides to several related carbohydrates by using the surface plasmon resonance (SPR) and the equilibrium dialysis techniques. Binding affinity studies, as well as assays of in vitro binding of the peptides to a sLeX-specific cell line, have shown that the tetrameric peptides bind to the cell surface sugars. 相似文献
70.
Jung Kwon Oh Jun Wu Mitchell A. Winnik Gary P. Craun Jude Rademacher Rajeev Farwaha 《Journal of polymer science. Part A, Polymer chemistry》2002,40(17):3001-3011
We describe the synthesis and characterization of three new polymerizable benzophenone derivatives [2‐acryloxy‐5‐methyl benzophenone ( 8 ), 4′‐dimethylamino‐2‐acryloxy‐5‐methyl benzophenone ( 9 ), and 4′‐dimethylamino‐2‐(β‐acryloxyethyl)oxy‐5‐methyl benzophenone ( 10 )]. We show that these monomers can successfully be incorporated into vinyl acetate (VAc) copolymer latex particles. These particles were prepared by semicontinuous emulsion polymerization and mini‐emulsion polymerization of VAc with butylacrylate (BA) for VAc/BA = 4/1 by weight. The two monomers 9 and 10 bearing the 4′‐dimethylamino group satisfy the important spectroscopic criteria required of a dye to serve as an acceptor chromophore for nonradiative energy transfer from phenanthrene (Phe) as the donor. Their UV absorption spectra suggest significant overlap with the emission spectrum of Phe, which can be incorporated into P(VAc‐co‐BA) latex through copolymerization with 9‐acryloxymethyl Phe ( 2 ). In addition, these chromophores provide a window in their absorption spectra for excitation of the Phe chromophore at 300 nm. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3001–3011, 2002 相似文献