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Electrophoretic Mobility (electrophoretic + mobility)
Kinds of Electrophoretic Mobility Terms modified by Electrophoretic Mobility Selected AbstractsPrinciple of a New Immunoassay Based on Electrophoretic Mobility of Poly(styrene/, - tert -butoxy- , -vinylbenzyl-polyglycidol) Microspheres: Application for the Determination of Helicobacter pylori IgG in Blood SerumMACROMOLECULAR BIOSCIENCE, Issue 1 2005Teresa Basinska Abstract Summary: The principle of a novel latex diagnostic test for the determination of antibodies against Helicobacter pylori in blood sera is described. The test is based on the measurement of the electrophoretic mobility of the microspheres with immobilized H. pylori antigens. The electrophoretic mobility of these microspheres depends on the concentration of the antibodies against H. pylori in suspending medium. Particles with hydrophilic polyglycidol in the surface layer were used for the test. The microspheres were obtained by an emulsifier-free emulsion copolymerization of styrene and , - tert -butoxy- , -vinylbenzyl-polyglycidol macromonomer (,=,220 nm, diameter polydispersity factor ,=,1.02). Activation of polyglycidol hydroxyl groups with cyanuric chloride allowed for covalent immobilization of H. pylori antigens. The fraction of H. pylori not specifically adsorbed onto the microspheres was negligible. Changes of the electrophoretic mobility of the microspheres with the surface concentration of the covalently immobilized H. pylori antigens ,,=,(1.6,±,0.3),·,10,3 g m,2 were suitable for the detection of the antibodies in the sera of patients with titer in the range (determined by the indirect ELISA test) from 1:500 to 1:32,000. [source] Hydrodynamic Size and Electrophoretic Mobility of Poly(styrene sulfonate) versus Molecular Weight,MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 19-20 2007Ute Böhme Abstract The effective charge of a macromolecule in solution is significantly smaller than the nominal charge, derived form the number of charged groups and the degree of dissociation. It is reduced by counterion condensation, shielding a considerable fraction of the macromolecules charge. As an example the influence of the molecular weight on hydrodynamic size and electrophoretic mobility of poly(styrene sulfonate) has been investigated. While from diffusion the hydrodynamic size is inferred, in a combination with electrophoresis NMR the effective charge is calculated. At low molecular weight the effective charge is equal to the nominal charge, in an intermediate range the effective charge is that predicted from counterion condensation theory, while at higher molecular weights it becomes considerably smaller. [source] Cover Picture: Electrophoresis 13'09ELECTROPHORESIS, Issue 13 2009Article first published online: 20 JUL 200 Issue 13 is a special issue on "CE and CEC of Amino Acids, Peptides and Proteins" assembling 19 papers on various topics including fast, high efficient and high sensitive "CE and CEC techniques for quality control and purity determination of native and (bio)synthetic amino acids, peptides and proteins, for monitoring of their synthesis, isolation, chemical derivatization and enzymatic digestion and also for investigation of their interactions with other molecules. New methodologies, such as electrodialysis for sample preparation, chiral ligand-exchange CE, immunoaffinity CE, affinity capillary isoelectric focusing, combination of transient isotachophoretic preconcentration with capillary zone electophoresis (CZE) analysis, two-dimensional CE-mass spectrometry (MS) separations and advances in high-sensitive CE-laser induced fluorescence (LIF) and CE-electrochemiluminescence detection schemes, are widely presented here. The applications of CE and CEC methods include chiral analysis of amino acids, determination of low abundant amino acids, peptides and proteins in complex matrices, such as human and animal body fluids and tissue biopsies, and profiling of cell lysates and recombinant proteins, e.g. birch pollen allergen and human interleukin 7. As can be seen from several contributions, preparation of new capillary coatings suppressing the adsorption of peptides and proteins to the fused silica capillary wall in their CZE analyses and/or increasing the selectivity of their open-tubular CEC separations remains a hot topic in the area of CE and CEC developments. In addition, it is shown that through the theoretical modelling of the CZE determined effective electrophoretic mobilities of proteins, the important parameters, such as charge, hydration and shape of their molecules, can be estimated." [source] Two variable semi-empirical and artificial neural-network-based modeling of peptide mobilities in CZE: The effect of temperature and organic modifier concentrationELECTROPHORESIS, Issue 5 2009Stefan Mittermayr Abstract This work was focused on investigating the effects of two separation influencing parameters in CZE, namely temperature and organic additive concentration upon the electrophoretic migration properties of model tripeptides. Two variable semi-empirical (TVSE) models and back-propagation artificial neural networks (ANN) were applied to predict the electrophoretic mobilities of the tripeptides with non-polar, polar, positively charged, negatively charged and aromatic R group characteristics. Previously published work on the subject did not account for the effect of temperature and buffer organic modifier concentration on peptide mobility, in spite of the fact that both were considered to be influential factors in peptide analysis. In this work, a substantial data set was generated consisting of actual electrophoretic mobilities of the model tripeptides in 30,mM phosphate buffer at pH 7.5, at 20, 25, 30, 35 and 40°C and at four different organic additive containing running buffers (0, 5, 10 and 15% MeOH) applying two electric field strengths (12 and 16,kV) to assess our mobility predicting models. Based on the Arrhenius plots of natural logarithm of mobility versus reciprocal absolute temperature of the various experimental setups, the corresponding activation energy values were derived and evaluated. Calculated mobilities by TVSE and back-propagation ANN models were compared with each other and to the experimental data, respectively. Neural network approaches were able to model the complex impact of both temperature and organic additive concentrations and resulted in considerably higher predictive power over the TVSE models, justifying that the effect of these two factors should not be neglected. [source] Characterization of voltage degradation in dynamic field gradient focusingELECTROPHORESIS, Issue 5 2008Jeffrey M. Burke Abstract Dynamic field gradient focusing (DFGF) is an equilibrium gradient method that utilizes an electric field gradient to simultaneously separate and concentrate charged analytes based on their individual electrophoretic mobilities. This work describes the use of a 2-D nonlinear, numerical simulation to examine the impact of voltage loss from the electrodes to the separation channel, termed voltage degradation, and distortions in the electric field on the performance of DFGF. One of the design parameters that has a large impact on the degree of voltage degradation is the placement of the electrodes in relation to the separation channel. The simulation shows that a distance of about 3,mm from the electrodes to the separation channel gives the electric field profile with least amount of voltage degradation. The simulation was also used to describe the elution of focused protein peaks. The simulation shows that elution under constant electric field gradient gives better performance than elution through shallowing of the electric field. Qualitative agreement between the numerical simulation and experimental results is shown. The simulation also illustrates that the presence of a defocusing region at the cathodic end of the separation channel causes peak dispersion during elution. The numerical model is then used to design a system that does not suffer from a defocusing region. Peaks eluted under this design experienced no band broadening in our simulations. Preliminary experimental results using the redesigned chamber are shown. [source] Effect of detergent on electromigration of proteins: CE of very low density lipoprotein receptor modules and viral proteinsELECTROPHORESIS, Issue 20 2007Leopold Kremser Dr. Abstract The different electrophoretic behavior of the members of two groups of proteins with respect to the absence or presence of detergent additives in the BGE was explored. Recombinant soluble concatemers of repeat 3 of the very low density lipoprotein (VLDL)-receptor fused at their N -terminus to maltose-binding protein (MBP) exhibited different electrophoretic mobilities in borate buffer (pH,8.3) in the absence and in the presence of dodecyl-PEG ether (D-PEG). This enabled the separation of the receptor fragments from MBP after enzymatic cleavage. In the presence of SDS, the mobilities of all proteins approached the same values with increase in detergent concentrations. In contrast, viral capsid proteins of a human rhinovirus (HRV) exhibited different migration in the presence of the additive. For the receptor proteins, extreme apparent high plate numbers were observed when the SDS concentration in the sample and the separation buffer differed. This effect might be erroneously interpreted as a high efficiency. However, it is due to the conductivity boundaries caused by the sample and leads to a total loss of separation. [source] CE analysis of the acidic organelles of a single cellELECTROPHORESIS, Issue 14 2007Yun Chen Abstract The properties of organelles within a cell have been shown to be highly heterogeneous. Until now, it has been unclear just how much of this heterogeneity is endemic to the organelle subpopulations themselves and how much is actually due to stochastic cellular noise. An attractive approach for investigating the origins of heterogeneity among the organelles of a single cell is CE with LIF detection (CE-LIF). As a proof of principle, in this report we optimize and use a single cell CE-LIF method to investigate the properties of endocytic (acidic) organelles. Our results show that the properties of individual acidic organelles containing Alexa Fluor® 488 Dextran suggest that there are two groups of CCRF-CEM cells: a group with a high dextran content per cell, and a group with a low dextran content per cell. Furthermore, the individual organelle measurements of the single cells allow us to compare in each group the distributions of doxorubicin content per acidic organelle and electrophoretic mobilities of these organelles. [source] Simultaneous determination of Zr(IV) and Hf(IV) by CE using precolumn complexation with a [PW11O39]7, ligandELECTROPHORESIS, Issue 10 2007Sadayuki Himeno Professor Abstract A CE method was developed for the simultaneous determination of Zr(IV) and Hf(IV) at trace levels. A lacunary Keggin-type [PW11O39]7, ligand reacted quantitatively with a mixture of trace amounts of Zr(IV) and Hf(IV) to form the so-called ternary Keggin-type anions [P(ZrIVW11)O40]5, and [P(HfIVW11)O40]5, in 0.010,M monochloroacetate buffer (pH,2.2). Since both ternary anions possessed different electrophoretic mobilities and high molar absorptivities in the UV region, Zr(IV) and Hf(IV) were determined simultaneously with direct UV detection at 258,nm. Each peak height was linearly dependent on the concentration of Zr(IV) or Hf(IV) in the range of 5.0×10,7,1.0×10,5,M; a detection limit of 2×10,7,M was achieved. The utility of the proposed CE method was demonstrated for the simultaneous determination of Zr(IV) and Hf(IV) in natural water samples with satisfactory results. [source] Capillary electrophoresis of polycationic poly(amidoamine) dendrimersELECTROPHORESIS, Issue 15 2005Xiangyang Shi Abstract Generation,2 to generation,5 poly(amidoamine) (PAMAM) dendrimers having different terminal functionalities were analyzed by capillary electrophoresis (CE). Polyacrylamide gel electrophoresis was also used to assess the composition of the individual generations for comparison with the CE results. Separation of PAMAMs can be accomplished by either using uncoated silica or silanized silica capillaries, although reproducibility is poor using the uncoated silica capillary. To improve run-to-run reproducibility, silanized capillary was used and various internal standards were also tested. Relative and normalized migration times of primary amine terminated PAMAM dendrimers were then determined using 2,3-diaminopyridine (2,3-DAP) as an internal standard. Using silanized capillaries and internal standards, the relative and normalized migration times are fully reproducible and comparable between runs. Apparent dimensionless electrophoretic mobilities were determined and the results were compared to theoretical calculations. It is concluded that for PAMAMs a complex separation mechanism has to be considered in CE, where the movement of the ions is due to the electric field, but the separation is rather the consequence of the adsorption/desorption equilibria on the capillary wall ("electrokinetic capillary chromatography"). The described method may be used for quality control and may serve as an effective technique to analyze polycationic PAMAM dendrimers and their derivatives with different surface modifications. [source] Detection of chlorinated quinones using interdigitated electrodes coupled with capillary electrophoresisELECTROPHORESIS, Issue 6 2003Keith B. Male Abstract An array of eight interdigitated microband gold electrodes (IDEs) has been developed together with electrophoretic separation for analysis of chlorinated hydroquinones (ClHQs) and benzoquinones (ClBQs). The IDE chip positioned very close to the separation capillary outlet served as an amplification/detection system without the requirement for frequent "capillary-electrode" alignment. ClHQs, electrophoretically migrating to the IDE surface, were oxidized at +1.1 V by seven electrodes of the array and then detected by the remaining electrode, poised at ,0.1 V. Conversely, ClBQs were detected at +1.1 V by the detecting electrode after having been reduced at the 7 adjacent electrodes poised at ,0.1 V. There was an amplification effect on both the detecting electrode as well as the adjacent electrodes because of the recycle between ClHQs and ClBQs. The detecting "amplification" current response was dependent on the potentials applied, the position of the detecting electrode on the array, the number of adjacent electrodes being used for recycling and the distance between the oxidative and reductive electrodes. Micellar electrokinetic chromatography (MEKC) separation of the analytes was achieved using 30 mM sodium dodecyl sulfate (SDS) with a detection limit in the range of 2,20 ,M. In addition to a facile "capillary-electrode" alignment, the important aspect described here was the capability of detecting through recycling a reduced compound (in the case of ClHQs) at a negative potential to circumvent fouling and electroactive interferences. An appealing feature was also the concurrent oxidation/reduction detection for each compound to ascertain peak assignment, as interfering compounds are less likely to exhibit the same oxidative/reductive characteristics and electrophoretic mobilities as the target analytes. [source] Nonlinear modeling of protein separation in a preparative-scale dynamic field gradient focusing instrumentAICHE JOURNAL, Issue 1 2009Noah I. Tracy Abstract Dynamic field gradient focusing (DFGF) uses an electric field gradient opposed by a counter-flow of buffer to separate milligrams of proteins according to their electrophoretic mobilities. A nonlinear model of protein separation in a preparative-scale DFGF device was developed to aid in refining the instrument's design and finding optimal run conditions prior to performing experiments. The model predicted the focal points of bovine serum albumin (BSA), and bovine hemoglobin (Hb) to within the 95% confidence intervals about the means of the experimental values. The resolution between the proteins in the model was 2.08, which was 3% less than the lower limit of the 95% confidence interval about the experimental value. The model predicted 67% more dispersion than was present in the experimental device, which made the simulated BSA peak 22% wider than the experimentally measured width. © 2008 American Institute of Chemical Engineers AIChE J, 2009 [source] Inhibitory effects of Hibiscus sabdariffa L extract on low-density lipoprotein oxidation and anti-hyperlipidemia in fructose-fed and cholesterol-fed ratsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 15 2004Chang-Che Chen Abstract Hibiscus sabdariffa L extract (HSE) is an aqueous extract of Hibiscus sabdariffa L flowers that is used as a local soft drink and medical herb in Taiwan. Oxidation of low-density lipoprotein (LDL) has been shown to increase the incidence of atherosclerosis. In this study, we determined the antioxidative activity of HSE on LDL oxidation by examining relative electrophoretic mobilities (REM) and thiobarbituric acid-reactive substances (TBARS). The data revealed an inhibitory effect of HSE on Cu2+ -mediated REM and TBARS. HSE exhibited a remarkable ability to reduce cholesterol degradation and ApoB fragmentation. Overall, HSE showed a high potency to inhibit the production of oxidized LDL induced by copper and, specifically, to reduce serum triglycerides in high-fructose diet (HFD) fed rats and serum cholesterol in high-cholesterol diet (HCD) fed animals. The levels of LDL and the ratio of LDL-cholesterol (LDL-C) to HDL-cholesterol (HDL-C) were reduced by HSE in both hyperlipidaemia models. Based on these findings, we suggest that HSE may be used to inhibit LDL oxidation and to prevent various types of hyperlipidaemia in HFD- or HCD-fed rats. Copyright © 2004 Society of Chemical Industry [source] Xis protein of the conjugative transposon Tn916 plays dual opposing roles in transposon excisionMOLECULAR MICROBIOLOGY, Issue 6 2001Douglas Hinerfeld The binding of Tn916 Xis protein to its specific sites at the left and right ends of the transposon was compared using gel mobility shift assays. Xis formed two complexes with different electrophoretic mobilities with both right and left transposon ends. Complex II, with a reduced mobility, formed at higher concentrations of Xis and appeared at an eightfold lower Xis concentration with a DNA fragment from the left end of the transposon rather than with a DNA fragment from the right end of the transposon, indicating that Xis has a higher affinity for the left end of the transposon. Methylation interference was used to identify two G residues that were essential for binding of Xis to the right end of Tn916. Mutations in these residues reduced binding of Xis. In an in vivo assay, these mutations increased the frequency of excision of a minitransposon from a plasmid, indicating that binding of Xis at the right end of Tn916 inhibits transposon excision. A similar mutation in the specific binding site for Xis at the left end of the transposon did not reduce the affinity of Xis for the site but did perturb binding sufficiently to alter the pattern of protection by Xis from nuclease cleavage. This mutation reduced the level of transposon excision, indicating that binding of Xis to the left end of Tn916 is required for transposon excision. Thus, Xis is required for transposon excision and, at elevated concentrations, can also regulate this process. [source] A cloning and expression analysis of pregnancy-associated glycoproteins expressed in trophoblasts of the white-tail deer placenta,MOLECULAR REPRODUCTION & DEVELOPMENT, Issue 11 2007Gretchen A. Brandt Abstract The pregnancy-associated glycoproteins (PAGs) are placental proteins that have been cloned from swine, sheep, goats, and cattle, but never from animals within the Cervidae family. The goal of this work was to characterize PAGs in white-tailed deer. Placenta and uterine tissues were collected from pregnant does at days 85 and 90 of pregnancy. RNA from cotyledons was used to amplify deer PAGs by RT-PCR. Ten distinct cDNAs were cloned and sequenced. Some normally conserved amino acids comprising the catalytic site were found to be altered in deer PAGs 4, 5, and 8; another PAG, (PAG-9) was a splice variant that lacked exon 7. In each case, these mutations would likely preclude proteolytic activity for these proteins. A phylogenetic analysis revealed that most of the deer PAGs fell within the ancient PAG grouping. The remainder fell within the more modern (BNC-specific) PAG group. Western blotting was performed with anti-PAG antibodies and this analysis revealed that deer PAGs comprise a heterogeneous group based on different antigenicities and electrophoretic mobilities. Immunohistochemistry and in situ hybridization revealed some unique localization patterns of PAGs in the deer placentome compared to those in other ruminants. Most notably, deer PAGs 4 and 5, which according to the phylogeny, are "ancient PAGs," were expected to be present in all trophoblasts; instead, they were localized to the BNC. Although many of the PAGs identified here are very similar to those in Bovidae, some are clearly distinct in their expression pattern and probably possess functional roles unique to cervid reproduction. Mol. Reprod. Dev. 74: 1355,1362, 2007. © 2007 Wiley-Liss, Inc. [source] Ca2+ -dependent in vitro contractility of a precipitate isolated from an extract of the heliozoon Actinophrys solCYTOSKELETON, Issue 2 2006Mikihiko Arikawa Abstract Contraction of axopodia in actinophrid heliozoons (protozoa) is induced by a unique contractile structure, the "contractile tubules structure (CTS)". We have previously shown that a cell homogenate of the heliozoon Actinophrys sol yields a precipitate on addition of Ca2+ that is mainly composed of filamentous structures morphologically identical to the CTS. In this study, to further characterize the nature of the CTS in vitro, biochemical and physiological properties of the precipitate were examined. SDS-PAGE analysis showed that the Ca2+ -induced precipitate was composed of many proteins, and that no proteins in the precipitate showed any detectable changes in electrophoretic mobility on addition of Ca2+. Addition of extraneous proteins such as bovine serum albumin to the cell homogenate resulted in cosedimentation of the proteins with the Ca2+ -induced precipitate, suggesting that the CTS has a high affinity for other proteins that are not related to precipitate formation. Appearance and disappearance of the precipitate were repeatedly induced by alternating addition of Ca2+ and EGTA, and its protein composition remained unchanged even after repeated cycles. When adhered to a glass surface, the precipitate showed Ca2+ -dependent contractility with a threshold of 10,100 nM, and this contractility was not inhibited by colchicine or cytochalasin B. The precipitate repeatedly contracted and relaxed with successive addition and removal of Ca2+, indicating that the contraction was controlled by Ca2+ alone with no need for any other energy supply. From our characterization of the precipitate, we concluded that its Ca2+ -dependent formation and contraction are associated with the unique contractile organelle, the "contractile tubules structure". Cell Motil. Cytoskeleton 2006. © 2005 Wiley-Liss, Inc. [source] Is natural selection a plausible explanation for the distribution of Idh- 1 alleles in the cricket Allonemobius socius?ECOLOGICAL ENTOMOLOGY, Issue 1 2006Diana L. Huestis Abstract., 1.,Allozyme alleles in natural populations have been proposed as either neutral markers of genetic diversity or the product of natural selection on enzyme function, as amino acid substitutions that change electrophoretic mobility may also alter enzyme performance. To address these possibilities, researchers have used both correlative analyses and empirical studies. 2.,Here, geographically structured variation of the enzyme isocitrate dehydrogenase (Idh- 1) in the striped ground cricket Allonemobius socius Scudder (Orthoptera: Gryllidae) is examined. The distributions of Idh- 1 alleles appear to be related to environmental gradients, as allele frequencies showed significant relationships with mean annual temperature and precipitation. Specifically, the slowest mobility allele was more frequent at colder temperatures, while the converse occurred for the fastest mobility allele. 3.,An exploratory experiment was performed to examine fitness effects of possessing different Idh- 1 alleles at two temperatures to test the hypothesis that the geographic structure of this locus may reflect environmental adaptation. Results showed that a significant interaction between temperature and Idh- 1 genotype affected the number of eggs laid, with success of homozygous individuals matching environmental expectations. 4.,The above results show that (1) variation in the frequency of Idh- 1 alleles is significantly related to environmental gradients in the eastern U.S.A. and (2) alternative alleles of Idh- 1 appear to influence the egg-laying ability of individuals differently depending on environmental temperature. Together, these results suggest that natural selection is a plausible mechanism underlying the distribution of Idh- 1 alleles in this species, although more detailed studies are needed. [source] The dependence of the electrophoretic mobility of small organic ions on ionic strength and complex formationELECTROPHORESIS, Issue 5 2010Stuart A. Allison Abstract The ionic strength dependence of the electrophoretic mobility of small organic anions with valencies up to ,3 is investigated in this study. Provided the anions are not too aspherical, it is argued that shape and charge distribution have little influence on mobility. To a good approximation, the electrophoretic mobility of a small particle should be equal to that of a model sphere with the same hydrodynamic radius and same net charge. For small ions, the relaxation effect (distortion of the ion atmosphere from equilibrium due to external electric and flow fields) is significant even for monovalent ions. Alternative procedures of accounting for the relaxation effect are examined. In order to account for the ionic strength dependence of a specific set of nonaromatic and aromatic anions in aqueous solution, it is necessary to include complex formation between the anion with species in the BGE. A number of possible complexes are considered. When the BGE is Tris-acetate, the most important of these involves the complex formed between anion and Tris, the principle cation in the BGE. When the BGE is sodium borate, an anion,anion (borate) complex appears to be important, at least when the organic anion is monovalent. An algorithm is developed to analyze the ionic strength dependence of the electrophoretic mobility. This algorithm is applied to two sets of organic anions from two independent research groups. [source] Measurement of electrophoretic mobility of cardiomyocytesELECTROPHORESIS, Issue 21 2009Ying Zhou Abstract The electrophoretic mobility (EPM) of rat cardiomyocytes with or without the treatment of neuraminidase was studied by cell electrophoresis. The EPM was found to change over a range from 0 to 8.67,,m,s,1/V,cm,1, depending on ionic strength, transmembrane potential, pH value, and/or surface charges. It is interesting that zero EPM was observed but reverse of the mobility was not. These results suggested that the negative charges carried on the cardiomyocyte surface might comprehensively consist of surface sialic acid, plasmalemma proteins, phospholipids, and transmembrane potential. The aberrant electrical double layer formed between the carried negative charges and adions had a big adsorption layer and a diffusion layer whose sizes changed circularly, making only negative charges be carried on the surface of living cardiomyocytes. The special structures on the surface of cardiomyocytes probably play a considerable role in the process of cardiac electrical activity. [source] Analysis of ,-globulin mobility on routine clinical CE equipment: Exploring its molecular basis and potential clinical utilityELECTROPHORESIS, Issue 15 2009Dieter Vanderschaeghe Abstract A study was conducted on the variability of ,-globulin mobility in serum protein electrophoresis and its molecular basis. We found that the migration time of ,-globulins can be reproducibly determined (CV=1.1%) on clinical CE equipment. Moreover, we found a significant difference (p<0.001) in the migration of ,-globulins between chronic liver disease patients (n=98) and a healthy reference group (n=47). Serum immunoglobulins were purified from these patients' sera using protein L -agarose and their glycosylation was studied using CE on a DNA sequencer. This glycomics approach revealed that several non-sialylated N-glycans show a moderate Pearson correlation coefficient (r=0.2,0.4) with the migration time of ,-globulins. Their sialylated structures correlate negatively (r=,0.2 to ,0.3). Immunoglobulins are significantly more sialylated in the healthy reference group compared with the patients (p<0.001). We estimated that sialylation heterogeneity contributes about 36% to the molecular variance (carbohydrates and amino acid composition) that affects the electrophoretic mobility of immunoglobulins. This is the first report on the migration time of ,-globulins on a clinical CE instrument and its potential clinical value to the routinely analyzed serum protein CE profiles. [source] Electrophoretic behaviors of human hepatoma HepG2 cellsELECTROPHORESIS, Issue 9 2009Jyh-Ping Hsu Abstract The electrophoretic mobility of HepG2 cells was measured and a charge-regulated model was proposed to simulate the results obtained. Here, a cell was simulated by a rigid core and an ion-penetrable membrane layer containing both acidic and basic functional groups. The influences of the key parameters, including the pH, the ionic strength, the thickness of the membrane layer of a cell, the density and the dissociation constant of the dissociable functional groups in the membrane layer, and the binding constant of divalent cations on the electrophoretic mobility of a cell were investigated. In particular, the role of the buffer used in the experiment was discussed; this effect was neglected in almost all the relevant theoretical analyses in the literature. We showed that the binding ability of divalent cations to the dissociated functional groups in the membrane layer of a cell ranks as Ca2+>Mg2+>hexamethonium. [source] Capillary electrophoretic and computational study of the complexation of valinomycin with rubidium cationELECTROPHORESIS, Issue 5 2009Sille Ehala Abstract This study is focused on the characterization of interactions of valinomycin (Val), a macrocyclic dodecadepsipeptide antibiotic ionophore, with rubidium cation, Rb+. Capillary affinity electrophoresis was employed for the experimental evaluation of the strength of the Val,Rb+ complex. The study involved the measurement of the change of effective electrophoretic mobility of Val at increasing concentration of Rb+ cation in the BGE. From the dependence of Val effective electrophoretic mobility on the Rb+ cation concentration in the BGE (methanolic solution of 100,mM Tris, 50,mM acetic acid, 0,1,mM RbCl), the apparent binding (stability) constant (Kb) of the Val,Rb+ complex in methanol was evaluated as log,Kb=4.63±0.27. According to the quantum mechanical density functional theory calculations employed to predict the most probable structure of Val,Rb+ complex, Val is stabilized by strong non-covalent bond interactions of Rb+ with six ester carbonyl oxygen atoms so that the position of the "central" Rb+ cation in the Val cage is symmetric. [source] Cover Picture: Electrophoresis 21'2008ELECTROPHORESIS, Issue 21 2008Article first published online: 14 NOV 200 This issue has an emphasis on "Proteomics and Related Topics". It comprises 11 research articles including the "Fast Track" article on the topic of proteomics, glycoproteomics, proteins and peptides. The "Fast Track" article describes a CE-LIF detection-based assay for the simultaneous measurements of the electrophoretic mobility, catalytic activity and the variation of activity over time of the individual enzymes molecules of Escherichia coli beta-galactosidase. The remaining 10 research articles of the Emphasis deal with the development of sensitive fluorescent staining for proteomic analysis, depletion of high abundance proteins form human serum, lectin affinity chromatography in the identification of rat urinary glycoproteome, lab-on-chip screening strategy of mouse serum samples prior to proteomics analysis, identification of proteins from membrane preparations, capillary coating for CE of proteins, characterization of rabbit liver apothioneins by CE-ESI-MS, quantitative analysis of recombinant protein charge heterogeneity by imaging CIEF, dye staining and immunodetection of proteins on a PVDF membrane, and separation of multiphosphorylated peptide isomers by CZE. [source] Electrophoresis of a charge-regulated toroid normal to a large diskELECTROPHORESIS, Issue 2 2008Jyh-Ping Hsu Abstract The electrophoresis of a charge-regulated toroid (doughnut-shaped entity) normal to a large disk is investigated under the conditions of low surface potential and weak applied electric field. The system considered is capable of modeling the electrophoretic behavior of various types of biocolloids such as bacterial DNA, plasmid DNA, and anabaenopsis near a perfectly conducting planar wall. The influences of the size of the toroid, the separation distance between the toroid and the disk, the charged conditions on the surfaces of the toroid and the disk, and the thickness of electric double layer on the electrophoretic mobility of the toroid are discussed. The results of numerical simulation reveal that under typical conditions the electrophoretic behavior of the toroid can be different from that of an integrated entity. For instance, if the surface of the toroid carries both acidic and basic functional groups, its mobility may have a local maximum as the thickness of double layer varies. We show that the electrophoretic behavior of the toroid is different, both qualitatively and quantitatively, from that of the corresponding integrated particle (particle without hole). [source] Enhanced pH-mediated stacking of anions for CE incorporating a dynamic pH junctionELECTROPHORESIS, Issue 20 2007Stacy D. Arnett Abstract A technique has been developed to enhance analyte focusing for CE for the analysis of physiological samples. High-ionic-strength samples are titrated to low-ionic-strength on-line using pH-mediated sample stacking in conjunction with a dynamic pH junction. This method concentrates analytes by reducing their electrophoretic mobility during field-amplification. Parameters responsible for enhanced focusing were investigated, and an enhanced pH-mediated stacking method was optimized for anionic nucleosides. The process results in ultra-narrow peak widths, for example, 0.28,s for thymidine with a 10,min analysis time. Peak width and resolution with the enhanced stacking method were also compared to normal base stacking and electrokinetic injection. With this technique, mass-loading capacity can be increased without degradation in peak shape and resolution is dramatically improved. [source] Light-emitting diode-compatible probes for indirect detection of anions in CEELECTROPHORESIS, Issue 19 2007Peter Balding Abstract A range of compounds were evaluated as probes for the indirect detection of inorganic ions using CE and light-emitting diodes (LEDs) as the light source. Emphasis was placed on examining probes likely to absorb strongly in the UV,Vis region near 350,430,nm as compounds, which absorb at longer wavelengths tend to be bulkier and adsorb onto the capillary wall. These probes should act as a replacement for the very effective but carcinogenic probe chromate. Two probes were identified and evaluated: p -nitrophenol and 4-hydroxy-3,5-dinitrobenzoic acid. The former showed the most potential with low-mobility anions, while the later had a moderate electrophoretic mobility and was more suitable for a wider mobility range of analytes. However, neither could match the efficiencies and LOD of chromate for the separation of the fast inorganic ions such as chloride, nitrate and sulphate. Nevertheless, application of the 4-hydroxy-3,5-dinitrobenzoic acid system to the determination of oxalate in Bayer liquors showed excellent sensitivity and selectivity. [source] Implementation of chemometric methodology in ACE: Predictive investigation of protein,ligand bindingELECTROPHORESIS, Issue 16 2007Grady Hanrahan Abstract An ACE predictive investigation of protein,ligand binding using a highly effective chemometric response surface design technique is presented. Here, Kd was estimated using one noninteracting standard which relates to changes in the electrophoretic mobility of carbonic anhydrase B (CAB, EC 4.2.1.1) on complexation with the ligand 4-carboxybenzenesulfonamide (CBSA) present in the electrophoresis buffer. Experimental factors including injection time, capillary length, and applied voltage were selected and tested at three levels in a Box,Behnken design. Statistical analysis results were used to create a mathematical model for response surface prediction via contour and surface plots at a given target response (Kd,=,1.19×10,6,M). As expected, there were a number of predicted solutions that reached our target response based on the significance of each factor at appropriate levels. The adequacy of the model was validated by experimental runs with the predicted model solution (capillary length,=,47,cm, voltage,=,11,kV, injection time,=,0.01,min) presented in detail as an example. [source] Anomalous electrophoretic behavior of a very acidic protein: Ribonuclease U2ELECTROPHORESIS, Issue 18 2005Lucía García-Ortega Abstract Ribonuclease U2 is a low-molecular-weight acidic protein with three disulfide bridges. This protein displays an anomalous electrophoretic behavior on standard SDS-PAGE. The electrophoretic mobility of the nonreduced protein roughly corresponds to its molecular mass while the migration of the reduced protein would be in accordance with the expected molecular mass of the protein dimer. This study reveals that the protein does not bind SDS under the SDS-PAGE conditions, its electrophoretic mobility being only determined by its electrostatic charge and hydrodynamic properties. In addition, the nonreduced protein cannot be blotted to a membrane. Unfolding of the protein upon reduction of its disulfide bridges enables electrotransference to membranes due to a restricted diffusion along the electrophoresis gel. [source] Analysis of poly(amidoamine)-succinamic acid dendrimers by slab-gel electrophoresis and capillary zone electrophoresisELECTROPHORESIS, Issue 15 2005Xiangyang Shi Abstract Ethylenediamine (EDA)-core poly(amidoamine) (PAMAM) succinamic acid dendrimers (Ex.SAH, where x refers to the generation) were synthesized and analyzed by polyacrylamide gel electrophoresis (PAGE), size-exclusion chromatography (SEC), potentiometric acid-base titration, and capillary zone electrophoresis (CZE). Various generations (E1.SAH,E7.SAH) PAMAMs and a succinamic acid terminated core-shell tecto(dendrimer) (E5(E3.SAH)n) were first analyzed by PAGE. PAGE results show that the relative mobilities of generation,2 to generation,7 dendrimers decreased with the increasing number of generations. The molecular mass of a generation,5 core generation,3 shell tecto(dendrimer) (denoted as E5(E3.SAH)n) was determined to be between the Mw of E6.SAH and E7.SAH. CZE analysis allowed the evaluation of electrophoretic properties of given-generation dendrimers. The electrophoretic mobilities of individual generations PAMAM polyanions are similar, indicating that the separation mainly depends on their approximately identical charge/mass ratio. The E5(E3.SAH)n tectodendrimer had a lower electrophoretic mobility, which was consistent with its lower charge/mass ratio. The combination of PAGE and CZE analysis provides an alternative and effective way to characterize this group of PAMAM-succinamic acid dendrimers. [source] Conformational effects on the performance and selectivity of a polymeric pseudostationary phase in electrokinetic chromatographyELECTROPHORESIS, Issue 4-5 2005Jonathan P. McCarney Abstract The effect of the conformation of a polymeric pseudostationary phase on performance and selectivity in electrokinetic chromatography was studied using an amphiphilic pH-responsive polymer that forms compact intramolecular aggregates (unimer micelles) at low pH and a more open conformation at high pH. The change in conformation was found to affect the electrophoretic mobility, retention, selectivity, and separation efficiency. The low-pH conformer has higher electrophoretic mobility and greater affinity for most solutes. The unimer micelle conformation was also found to provide a solvation environment more like that of micelles and other amphiphilic self-associative polymers studied previously. It was not possible to fully characterize the effect of conformation on efficiency, but very hydrophobic solutes with long alkyl chains appeared to migrate with better efficiency when the unimer micelle conformation was employed. The results imply that polymers with a carefully optimized lipophilic-hydrophilic balance that allow self-association will perform better as pseudostationary phases. In addition, the results show that electrokinetic chromatography is a useful method for determining the changes in solvation environment provided by stimuli-responsive polymers with changes in the conditions. [source] Comparison of different algorithms to calculate electrophoretic mobility of analytes as a function of binary solvent compositionELECTROPHORESIS, Issue 10 2003Abolghasem Jouyban Abstract Ten different mathematical models representing the electrophoretic mobility of analytes in capillary electrophoresis in mixed solvents of different composition have been compared using 32 experimental data sets. The solvents are binary mixtures of water-methanol, water-ethanol and methanol-ethanol, respectively. Mean percentage deviation (MPD), overall MPD (OMPD) and individual percentage deviation (IPD) have been considered as comparison criteria. The results showed that a reorganized solution model, namely the combined nearly ideal binary solvent/Redlich-Kister equation, is the most accurate model among other similar models concerning both correlation ability and prediction capability. [source] | |||||||||||||||||||||||||||||||