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11.
Berkowitz SA Zhong H Berardino M Sosic Z Siemiatkoski J Krull IS Mhatre R 《Journal of chromatography. A》2005,1079(1-2):254-265
A simple high-resolution capillary zone electrophoresis (CZE) method capable of rapidly assessing the micro-heterogeneity of a 24 kDa molecular weight glycoprotein, has been developed. Separation is carried out using a bare silica capillary at a pH of 2.5 in a commercially available electrophoresis buffer system composed of triethanolamine and phosphoric acid. Over 30 peaks were detected within a run time of 15 min using a 27 cm capillary and approximately 60 peaks were detected using a 77 cm capillary. Although most of the peaks arise from differences in the oligosaccharide structures present on the one glycosylation site on this molecule, other forms of micro-heterogeneity due to the presence of the nonglycosylated form of this glycoprotein and various types of chemical degradation, e.g., deamidation, are also responsible for the multitude of peaks observed. Although the exact chemical identity of each peak in the resulting electropherogram of this glycoprotein is not known, useful information can be obtained for assessing comparability, stability, and batch consistency. Factors impacting the resolution, precision, accuracy, and robustness of the assay are also discussed along with inherent advantages and limitations associated with measuring the micro-heterogeneity of intact glycoproteins. 相似文献
12.
Polenov Yu. V. Pushkina V. A. Egorova E. V. Labutin A. N. Khalizov R. L. 《Kinetics and Catalysis》2002,43(4):465-468
A kinetic model of the decomposition of sodium hydroxymethanesulfinate (rongalite) in aqueous solution at an initial value of pH 7.9 was considered. This multistep reaction was found to include oxidation decomposition in a solution surface layer and bulk reactions both with and without the participation of oxygen. To evaluate the parameters of this model, it was modified over three time intervals. The adequacy of this model to experimental data supported the hypothesis on the catalytic effect of active sulfur in the decomposition of rongalite. 相似文献
13.
Millea KM Kass IJ Cohen SA Krull IS Gebler JC Berger SJ 《Journal of chromatography. A》2005,1079(1-2):287-298
The performance characteristics of multidimensional liquid chromatographic protein separations were evaluated using on-line electrospray mass detection, and a novel workflow for automated LC/MS data processing. Two-dimensional ion exchange/reversed-phase LC separations of Escherichia coli cytosol were conducted using either a continuous linear or discontinuous step gradient in the first dimension. Chromatographic profiles of the top 100 most abundant components were characterized to assess overall separation reproducibility within each mode, and to characterize differences in component distribution between the two modes of operation. Analysis of the resulting data indicates that multidimensional separations of complex protein mixtures can be done reproducibly. Furthermore, under the conditions employed within this study, a linear first dimension gradient was more effective at fractionating the protein mixture, distributing fewer major components to multiple second dimension cycles than an equivalent step gradient. The application of on line mass spectrometry, and automated processing of the resulting data, proved valuable for producing component level analysis of multidimensional protein separations. 相似文献
14.
The texture of the starting high-silica zeolite ZSM-5 and its decationated samples is studied by the low-temperature adsorption method. Mesopores with a diameter of 42 Å are found. Decationation of the zeolite is accompanied by an increase in the specific surface area and pore volume. It is suggested that the textural changes found are due to the removal of admixtures from some pores. A model for the formation of the secondary pore system is proposed. The secondary porosity is suggested to be due to the coordination of the zeolite crystals through the primary particles of aluminum hydroxide located on the surface of the zeolite crystals. The influence of the decationation conditions on the textural characteristics of ZSM-5 is shown. 相似文献
15.
16.
The Michael condensation in the series of 5-aryl-3H-furan-2-ones with chalcones containing electron-donating substituents was studied. In the case of ,-unsaturated ketones containing an electrondonating substituent, the reaction does not stop at the stage of formation of 1,5-dicarbonyl compounds but is accompanied by intramolecular cyclodehydration yielding a new series of furo[2,3-b]-4H-pyrans. A mechanism of formation of these products was suggested. The structure of reaction products was proved by IR and 1H NMR spectroscopy. 相似文献
17.
Lamberov A. A. Levin O. V. Egorova S. R. Evstyagin D. A. Aptikasheva A. G. 《Russian Journal of Applied Chemistry》2003,76(3):351-357
The method of low-temperature adsorption of nitrogen was applied to study structural characteristics of commercial peptized aluminum hydroxides. An increase or decrease in the porometric volume, depending on the nature and concentration of the peptizing agent, was analyzed. The phenomena observed are explained in terms of the mechanism suggested for formation of the pore system in commercial aluminum hydroxides. The dependence of the physicomechanical properties of active aluminum oxide on synthesis conditions and texture characteristics of commercial aluminum hydroxides was studied. 相似文献
18.
L. B. Naumova L. A. Egorova A. A. Slivinskaya 《Russian Journal of Applied Chemistry》2006,79(2):236-240
The influence exerted by modifying additives of inorganic nature on the hydrophilicity of peats from the Orlovskoe deposit in Tomsk oblast and on their thermal stability was studied. The acid-base, equilibrium, and kinetic properties of the starting peat samples and those modified with solutions of iron(III) and aluminum chlorides were examined. Their physicochemical parameters were determined: total exchange capacity, acidity by acid and basic groups, relative humidity, distribution coefficients, effective diffusion coefficients, and activation energy. The effect of modifying cations on the thermal decomposition of peat was analyzed. 相似文献
19.
Sharutin V. V. Sharutina O. K. Egorova I. V. Ivanenko T. K. Bel'skii V. K. 《Russian Journal of General Chemistry》2002,72(1):44-45
The reaction of triphenylbismuth dichloride with sodium fluoride in acetone leads to formation of triphenylbismuth difluoride in 73% yield. The X-ray diffraction data show that the bismuth atom in the two symmetrically independent molecules of bismuth difluoride has a trigonal-bipyramidal coordination with equatorial fluorine atoms. The Bi-F and Bi-C distances are 2.53(1)-2.59(1) and 2.10(3)-2.22(2) Å, respectively, and the FBiF angle is 175.1(5)°. 相似文献
20.
V. A. Sedavkina V. A. Morozova A. Yu. Egorova R. G. Savkin 《Russian Chemical Bulletin》1995,44(10):1914-1916
Treatment of 5-alkyl-3H-furan-2-ones and 5-alkyl-3H-thiophen-2-ones with dichlorocarbene under conditions of phase-transfer catalysis at 20–90 °C results in insertion of the carbene at the C=C bond followed by skeletal rearrangement.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1995–1997, October, 1995. 相似文献