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171.
Nazrul Islam Peter M. Campbell Thomas J. V. Higgins Hisashi Hirano Raymond J. Akhurst 《Electrophoresis》2009,30(11):1863-1868
Differential in‐gel electrophoresis showed contrasting effects of the transgenic expression of an α‐amylase inhibitor from beans on the proteomes of two pea cultivars. One cultivar showed minor changes relative to its non‐transgenic parent with only one protein changing by more than about twofold. Changes in the abundance of certain endogenous proteins in the other cultivar were of greater number and magnitude with some endogenous proteins undetected while some new protein spots appeared in the transgenic proteome. The sets of proteins with altered expression were generally different between the two cultivars. Some of the proteins that were differentially expressed were identified by MS. Most were seed storage globulins, which are sited together with the transgenic product. Some of the changes may be due to alterations in expression levels but there were also changes due to post‐translational processing. 相似文献
172.
The thermodynamics of binding of Me-alpha(-GalNAc, Gal-beta-1-3GalNAc-alpha-O-Me (T-antigen-alpha), Gal-beta-1-3GalNAc and Gal-alpha-1-6Glc (mellibiose) to Artocarpus hirsuta lectin was studied using fluorescence spectroscopy. The binding affinities of the saccharides are in the order Gal-beta-1-3GalNAc-alpha-O-Me > Me-alpha-GalNAc > Me-alpha-Gal > Gal-beta-1-3GalNAc > Gal-alpha-1-6Glc. The binding affinities were comparable to those for jacalin. However, binding of the saccharides to the A. hirsuta lectin was not affected as strongly by temperature as observed in jacalin and the trend was found to be reversed. Values for AH and AS were found to be positive in A. hirsuta lectin-disaccharide binding despite similar binding affinities. Thus, with 99% structural and 96% sequence homology, with similar sugar specificity and affinity, the energetics of the disaccharide binding of the two lectins seem to be different. Me-alpha-GalNAc binding to A. hirsuta lectin is enthalpically driven, because the association constant decreases with increasing temperature. However, the binding of the T-antigen disaccharides and mellibiose disaccharides to the lectin is entropically driven. The difference in the molecular associations in the packing and variation of the C-terminal length of the beta chain of the A. hirsuta lectin could be reflected in the different disaccharide binding energetics. 相似文献
173.
Shi X Bányai I Rodriguez K Islam MT Lesniak W Balogh P Balogh LP Baker JR 《Electrophoresis》2006,27(9):1758-1767
Generation 5 ethylenediamine (EDA)-cored poly(amidoamine) (PAMAM) dendrimers (E5, E denotes the EDA core and 5 the generation number) with different degrees of acetylation and carboxylation were synthesized and used as a model system to investigate the effect of charge and the influence of dendrimer surface modifications on electrophoretic mobility (EM) and molecular distribution. The surface-modified dendrimers were characterized by size-exclusion chromatography, 1H NMR, MALDI-TOF-MS, PAGE, and CE. The focus of our study was to determine how EM changes as a function of particle charge and molecular mass, and how the molecular distribution changes due to surface modifications. We demonstrate that partially modified dendrimers have much broader migration peaks than those of fully surface functionalized or unmodified E5 dendrimers due to variations in the substitution of individual dendrimer surfaces. EM decreased nonlinearly with increases in surface acetylation for both PAMAM acetamides and PAMAM succinamic acids, indicating a complex migration activity in CE separations that is not solely due to charge/mass ratio changes. These studies provide new insights into dendrimer properties under an electric field, as well as into the characterization of dendrimer-based materials being developed for medical applications. 相似文献
174.
175.
1H-1,2,3-triazole,a promising precursor for chemical vapor deposition of hydrogenated carbon nitride
Md. Nizam Uddin Iqbal Ahmed Siddiquey Md. Jahurul Islam Osama A. Fouad Masamitsu Nagano 《Journal of Crystal Growth》2009,311(13):3528-3532
Well-crystallized hydrogenated carbon nitride thin films have been prepared by microwave plasma enhanced chemical vapor deposition (MWPECVD). 1H-1,2,3-triazole+N2 and Si (1 0 0) were used as precursor and substrate, respectively. Substrate temperature during the deposition was recorded to be 850 °C. The synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photo-electron spectroscopy (XPS) analyses. The plasma compositions were checked by optical emission spectroscopy (OES). XRD observation strongly suggests that the films contain polycrystalline carbon nitride with graphitic structure of (1 0 0), (0 0 2), (2 0 0) and (0 0 4). XPS peak quantification reveals that the atomic ratio of the materials C:N:O:Si is 32:41:18:9. X-ray photo-electron peak deconvolution shows that the most dominant peak of C (1s) and N (1s) narrow scans correspond to sp2 hybrid structure of C3N4. These observations indicate that 1H-1,2,3-triazole favors the formation of hydrogenated carbon nitride with graphitic phase by CVD method and thus is in good agreement with XRD results. SEM of surface and OES of plasma also support the formation of polycrystalline carbon nitride films from 1H-1,2,3-triazole+N2 by CVD. 相似文献
176.
IR Bothwell K Islam Y Chen W Zheng G Blum H Deng M Luo 《Journal of the American Chemical Society》2012,134(36):14905-14912
Posttranslational methylation by S-adenosyl-l-methionine(SAM)-dependent methyltransferases plays essential roles in modulating protein function in both normal and disease states. As such, there is a growing need to develop chemical reporters to examine the physiological and pathological roles of protein methyltransferases. Several sterically bulky SAM analogues have previously been used to label substrates of specific protein methyltransferases. However, broad application of these compounds has been limited by their general incompatibility with native enzymes. Here we report a SAM surrogate, ProSeAM (propargylic Se-adenosyl-l-selenomethionine), as a reporter of methyltransferases. ProSeAM can be processed by multiple protein methyltransferases for substrate labeling. In contrast, sulfur-based propargylic SAM undergoes rapid decomposition at physiological pH, likely via an allene intermediate. In conjunction with fluorescent/affinity-based azide probes, copper-catalyzed azide-alkyne cycloaddition chemistry, in-gel fluorescence visualization and proteomic analysis, we further demonstrated ProSeAM's utility to profile substrates of endogenous methyltransferases in diverse cellular contexts. These results thus feature ProSeAM as a convenient probe to study the activities of endogenous protein methyltransferases. 相似文献
177.
Imran SadiqImran Khan Faiza AenM.U. Islam M.U. Rana 《Physica B: Condensed Matter》2012,407(8):1256-1261
A series of single phase W-type Sr3−xCexFe16O27 (x=0, 0.02, 0.04, 0.06, 0.08, 0.10) hexagonal ferrites prepared by the Sol-Gel method was sintered at 1050 °C for 5 h. The X-ray diffraction analysis reveals that all the samples belong to the family of W-type hexagonal ferrites. The c/a ratio falls in the range of W-type hexagonal ferrites. The grain size was measured by SEM varies from 0.7684 to 0.4366 μm which shows that the Ce3+ substituted samples have smaller grain size than pure ferrite Sr3Fe16O27 which results from the difference in ionic radii of Ce3+ (1.034 Å) and Sr2+ (1.12 Å). The room temperature resistivity of the present samples varies from 6.5×108 to 272×108 Ω-cm. The coercivity increases from 1370 to 1993 Oe which is consistent with the decrease in grain size. The coercivity values indicate that the present samples fall in the range of hard ferrites. The large value of Hc may be due to domain wall pinning at the grain boundaries. 相似文献
178.
179.
S.M. Islam Anupam Singha Roy Paramita Mondal Kazi Tuhina Manir Mobarak John Mondal 《Tetrahedron letters》2012,53(2):127-131
A new polymer-anchored Cu(II) complex has been synthesized and characterized. The catalytic performance of the complex has been tested for the oxidation of sulfides and in oxidative bromination reaction with hydrogen peroxide as the oxidant. Sulfides have been selectively oxidized to the corresponding sulfoxides in excellent yields and in the presence of KBr as the bromine source, organic substrates have been selectively converted to mono bromo substituted compounds using polymer-anchored Cu(II) catalyst. This catalyst showed excellent catalytic activity, high selectivity, and recyclability. The polymer-anchored Cu(II) catalyst could be easily recovered by filtration and reused more than five times without appreciable loss of its initial activity. 相似文献
180.
The development of the thermo-viscous fingering instability of miscible displacements in homogeneous porous media is examined. In this first part of the study dealing with stability analysis, the basic equations and the parameters governing the problem in a rectilinear geometry are developed. An exponential dependence of viscosity on temperature and concentration is represented by two parameters, thermal mobility ratio β T and a solutal mobility ratio β C , respectively. Other parameters involved are the Lewis number Le and a thermal-lag coefficient λ. The governing equations are linearized and solved to obtain instability characteristics using either a quasi-steady-state approximation (QSSA) or initial value calculations (IVC). Exact analytical solutions are also obtained for very weakly diffusing systems. Using the QSSA approach, it was found that an increase in thermal mobility ratio β T is seen to enhance the instability for fixed β C , Le and λ. For fixed β C and β T , a decrease in the thermal-lag coefficient and/or an increase in the Lewis number always decrease the instability. Moreover, strong thermal diffusion at large Le as well as enhanced redistribution of heat between the solid and fluid phases at small λ is seen to alleviate the destabilizing effects of positive β T . Consequently, the instability gets strictly dominated by the solutal front. The linear stability analysis using IVC approach leads to conclusions similar to the QSSA approach except for the case of large Le and unity λ flow where the instability is seen to get even less pronounced than in the case of a reference isothermal flow of the same β C , but β T = 0. At practically, small value of λ, however, the instability ultimately approaches that due to β C only. 相似文献