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Reverse-phase high-performance liquid chromatography was utilized to separate efficiently and rapidly a standard mixture of various radiolabeled O-methylated mannitols and O-methylfucitol commonly encountered when vertebrate asparagine-linked oligosaccharides are subjected to permethylation, hydrolysis, and reduction with NaBH4. The following reduced, radioactive O-methylhexitols were resolved: 2,4-, 3,4-, and 3,6-di-O-methylmannitols; 3,4,6-tri-O-methylmannitol, 2,3,4-tri-O-methylfucitol, and 2,3,4,6-tetra-O-methylmannitol. To demonstrate the utility of this separation method in the analysis of metabolically radiolabeled asparagine-linked oligosaccharides, mouse lymphoma BW 5147 cells were metabolically radiolabeled with [2-3H]mannose and their glycopeptides prepared by Pronase digestion and fractionated by serial chromatography on immobilized lectins. Each fraction was subjected to methylation and hydrolysis, the released monosaccharides were reduced, and the radioactive O-methylhexitols were separated by reverse-phase HPLC. The relative amounts of the O-methylhexitols in each glycopeptide fraction analyzed were similar to those values determined by a combination of other separation systems. 相似文献
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Distribution of the catabolic transposon Tn5271 in a groundwater bioremediation system. 总被引:4,自引:2,他引:2
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The distribution of Tn5271-related DNA sequences in samples of groundwater and a groundwater bioremediation system at the Hyde Park (Niagara Falls, N.Y.) chemical landfill site was investigated. PCR amplification of target sequences within the cha genes of Tn5271 revealed similar sequences in the groundwater community and in samples from the sequencing batch reactors treating that groundwater. Cell dilution combined with PCR amplification indicated that cha sequences were carried in about 1 of 10 culturable bacteria from the treatment system. Characterization of isolates involved in chlorobenzoate and toluene biodegradation in the treatment system indicated that two phenotypic clusters, Alcaligenes faecalis type 2 and CDC group IVC-2, contained all of the Tn5271 probe-positive isolates from the community. These two groups differed phenotypically from recipient groups isolated following horizontal transfer of pBRC60 (Tn5271) in pristine freshwater microcosms. A genetic rearrangement in Tn5271 attributable to the intramolecular transposition of the flanking element IS1071R was detected in an isolate from the treatment system. Comparison of the structure of the intramolecular transposition derivative from groundwater isolate OCC13(pBRC13) with a laboratory-derived intramolecular transposition derivative of pBRC60 revealed similarities. The rearrangement was shown to increase the stability of the plasmid under starvation conditions. 相似文献
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The repeated-pairs of surnames in marriages (RP) approach is applied to the population of Tiszaszalka in north-eastern Hungary. The results indicate that: (1) lineage-like behaviour in mate choice results in population subdivision in both the Catholics and the Protestants of the village; (2) unlike in some other Tiszahat villages, the isonymous and the repeating unions in Tiszaszalka occur in different lineages so, in neither of these subpopulations are isonymous and repeating unions monopolised by a few lineages; (3) religious affilitation influences the mating structure of the population as measured by RP summary scores. 相似文献
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Pascal Y Andrianjara CR Auclair E Avenel N Bertin B Calvet A Féru F Lardon S Moodley I Ouagued M Payne A Pruniaux MP Szilagyi C 《Bioorganic & medicinal chemistry letters》2000,10(1):35-38
A novel series of benzodiazepine derivatives have been discovered as inhibitors of PDE4 enzymes. We have found that our compounds are selective versus other PDE enzymes, and that the activity can be modulated by specific structural modifications. One compound exhibited a strong eosinophilic infiltration inhibiting action on sensitized Brown-Norway rats (compound 9, 5.1 mg/kg p.o.), moreover this compound is not emetic at 3 mg/kg i.v. 相似文献
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X-ray absorption spectroscopy at the sulfur K-edge (2.4-2.6keV) provides a sensitive and specific technique to identify S-nitroso compounds, which have significance in nitric oxide-based cell signaling. Unique spectral features clearly distinguish the S-nitroso-form of a cysteine residue from the sulfhydryl-form or from a methionine thioether. Comparison of the sulfur K-edge spectra of thiolate, thiol, thioether, and S-nitroso thiolate compounds indicates high sensitivity of energy positions and intensities of XAS pre-edge features as determined by the electronic environment of the sulfur absorber. A new experimental setup is being developed for reaching the in vivo concentration range of S-nitroso thiol levels in biological samples. 相似文献
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The measurement of nanogram amounts of acetylcholine in tissues by pyrolysis gas chromatography 总被引:3,自引:3,他引:0
Abstract— A method previously described for measuring ACh in biological effluents has been simplified and extended for use with tissues. The tissue is homogenized in acetonitrile containing propionylcholine as the internal standard and after centrifugation the acetonitrile is removed by shaking with toluene. To the aqueous solution is added a solution of KI-I2 to precipitate the quaternary compounds. The precipitate is dissolved in aqueous acetonitrile and then drawn through a small column of ion-exchange resin to convert the periodides of the quaternary compounds to chlorides which are then simultaneously pyrolysed and gas chromatographed. On the column the pyrolytic product of choline has a slower retention time than that of acetylcholine; under these circumstances the choline present in tissues does not obscure the measurement of acetylcholine. Specificity was demonstrated by several procedures including mass spectroscopy. The method can measure 25 ng (171 pmoles) of acetylcholine in extracts of brain, simply, and with high reproducibility. With the usual gas chromatograph, 16 samples can be run in a working day. The content of acetylcholine in rat brain was 26.4 nmol/g or almost precisely the values found with other gas chromatographic methods. The pyrolytic method was shown to be applicable to the detection of biologically interesting substances other than choline esters, including betaine, carnitine and the non- quaternary compound, ?-aminobutyric acid, which is readily converted to a volatile compound (probably its methyl ester) when pyrolysed in the presence of tetramethylammonium hydroxide. Of additional general interest is the demonstration of the advantages of acetonitrile as a solvent for extracting water-soluble compounds from tissues. 相似文献
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Dalia Rokhsana David M. Dooley Robert K. Szilagyi 《Journal of biological inorganic chemistry》2008,13(3):371-383
A systematic in silico approach has been employed to generate sound, experimentally validated active-site models for galactose oxidase (GO) using a hybrid density functional, B(38HF)P86. GO displays three distinct oxidation states: oxidized [Cu(II)-Y*]; semireduced [Cu(II)-Y]; and reduced [Cu(I)-Y]. Only the [Cu(II)-Y*] and the [Cu(I)-Y] states are assumed to be involved in the catalytic cycle, but their structures have not yet been determined. We have developed several models (1-7) for the [Cu(II)-Y*] state that were evaluated by comparison of our computational results with experimental data. An extended model system (6) that includes solvent molecules and second coordination sphere residues (R330, Y405, and W290) is essential to obtain an experimentally correct electronic structure of the active site. The optimized structure of 6 resulted in a five-coordinate Cu site with a protein radical centered on the Tyr-Cys cofactor. We further validated our converged model with the largest model (7) that included additional outer-sphere residues (Q406, H334, Y329, G513, and T580) and water molecules. Adding these residues did not affect significantly the active site's electronic and geometric structures. Using both 6 and 7, we explored the redox dependence of the active-site structure. We obtained four- and three-coordinate Cu sites for [Cu(II)-Y] and [Cu(I)-Y] states, respectively, that corroborate well with the experimental data. The relative energies of these states were validated by a comparison with experimental redox potentials. Collectively, our computational GO models well reproduce the physicochemical characteristics of the individual states, including their redox behaviors. 相似文献
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Walter Wurm Katrin Vogel Anna Holl Christoph Ebner Dietmar Bayer Sabrina M?rkl Istvan-Szilard Szilagyi Erich Hotter Hans-Peter Kapfhammer Peter Hofmann 《PloS one》2016,11(3)