Electrophoretic mobility concentration

Fig. 1. Electrophoretic mobility of Hind lll-restrict fragments of X DNA after UV irradiation (A) and DNA electrophoregram trace (B) 1 - control, 2 - after UV irradiation for 3 hours (3.64 J/m2 ), 3, 4 - the same in the presence of Q-AR in concentrations of ICHM and lO M, 5, 6 - the same in the presence of Q-AR at concentrations of lO M and lO M. The arrow shows...

Overbeek and Booth [284] have extended the Henry model to include the effects of double-layer distortion by the relaxation effect. Since the double-layer charge is opposite to the particle charge, the fluid in the layer tends to move in the direction opposite to the particle. This distorts the symmetry of the flow and concentration profiles around the particle. Diffusion and electrical conductance tend to restore this symmetry however, it takes time for this to occur. This is known as the relaxation effect. The relaxation effect is not significant for zeta-potentials of less than 25 mV i.e., the Overbeek and Booth equations reduce to the Henry equation for zeta-potentials less than 25 mV [284]. For an electrophoretic mobility of approximately 10 X 10 " cm A -sec, the corresponding zeta potential is 20 mV at 25°C. Mobilities of up to 20 X 10 " cmW-s, i.e., zeta-potentials of 40 mV, are not uncommon for proteins at temperatures of 20-30°C, and thus relaxation may be important for some proteins. 

Rodbard and Chrambach [77,329] developed a computer program that allows the determination of molecular parameters, i.e., free mobility, molecular radii, molecular weight, and charge or valence, from measured electrophoretic mobilities in gels with different monomer concentrations. For a set of mobility versus gel concentration data they used the Ferguson [18,115,154] equation to obtain the retardation constant from the negative slope and the free mobility from the extrapolated intercept. From the retardation constant they determined the molecular radius using... 

The standard Rodbard-Ogston-Morris-Killander [326,327] model of electrophoresis which assumes that u alua = D nlDa is obtained only for special circumstances. See also Locke and Trinh [219] for further discussion of this relationship. With low electric fields the effective mobility equals the volume fraction. However, the dispersion coefficient reduces to the effective diffusion coefficient, as determined by Ryan et al. [337], which reduces to the volume fraction at low gel concentration but is not, in general, equal to the porosity for high gel concentrations. If no electrophoresis occurs, i.e., and Mp equal zero, the results reduce to the analysis of Nozad [264]. If the electrophoretic mobility is assumed to be much larger than the diffusion coefficients, the results reduce to that given by Locke and Carbonell [218]. 

Waldmann-Meyer, HK, Protein Ion Equilibria, Total Evaluation of Binding Parameters and Net Charge from the Electrophoretic Mobility as a Function of Ligand Concentration. In Recent Developments in Chromatography and Electrophoresis Frigerio, A McCamish, M, eds. Elsevier Scientific Amsterdam, 1980 Vol. 10, p 125. 

For the work described below, only 600 pi (6 mg) of gland extract, obtained from the posterior gland, were available. The active protein was subsequently determined to be present at a concentration of about 0.5%, representing less than 100 pg (1 nmol) of hementin. The remainder of the extract consisted of several hundred inactive proteins and peptides. While the protein composition and cell types of the anterior and posterior glands are very different, the electrophoretic mobility of the active enzyme from... 

It is interesting to compare these results with the electrophoretic measurements made under identical electrolyte concentrations. Figure 8 shows that the variation of electrophoretic mobility with sodium chloride concentration is different for the bare and the PVA-covered particles. For the bare particles, the mobility remains constant up to a certain salt concentration, then increases to a maximum and decreases sharply, finally approaching zero. The maximum in electrophoretic mobility-electrolyte concentration curve with bare particles has been explained earlier (21) by postulating the adsorption of chloride ions on hydrophobic polystyrene particles. In contrast, for the PVA-covered particles, the mobility decreases with increasing electrolyte concentration until it approaches zero at high salt concentration. 

Figure 8. Electrophoretic mobility versus electrolyte concentration (NaCl) for different-size particles (o) 190nm particles (A) 400nm particles open points for bare particles and closed points for particles covered with Vinol-107 at saturation.

Ionic strength BSA concentration in yg/cm2 t in Distance Electrophoretic mobility... 

Influence of the Surface Concentration of BSA. Compared to the corrected moving boundary electrophoretic mobility of BSA in solution, the mobility of BSA adsorbed onto glass is considerably faster at all ionic strengths at 1.96 pg/cm2 and somewhat faster at lower ionic strengths 1.38 pg/cm2. However, at lower adsorption densities (1.05 and 0.64 pg/cm2), the adsorbed BSA moves more slowly in the applied electric field than BSA in moving boundary electrophoresis under otherwise identical conditions, and at the lowest surface adsorption (0.64 pg/cm2) the mobility of the adsorbed BSA are even somewhat slower than in cellulose acetate gel at all conditions of ionic strength investigated. 

As the redispersion region may be the result of a charge reversal, the electrophoretic mobilities of the MCC sols as a function of NaCl concentration were determined. No charge reversal was detected and the mobility of the particles decreased from 3.5 to 2.6 mobility units in a linear manner with increasing salt concentration indicating that the redispersion region was not caused by charge reversal. 

Starting from the observations that HpHb has a much higher peroxidase activity at acid pH and is more resistant to I2 than Hb, Jayle (J5) devised two similar methods for measuring Hp—the activation and the saturation methods—which are still in common use. The difference between the electrophoretic mobility of HpHb and of Hb was also later (L10) utilized to estimate the serum Hp concentration. The general agreement between results obtained by both methods was shown by Nyman (N5). 

Figure 2. Electrophoretic mobility of Corynebacterium versus pH. The general trend of the markers for each KNO3 concentration (A = 0.001 O = 0.01 and x = O.lmoldm-3) is indicated with an auxiliary line. Redrawn from reference [22]...

Carrique F, Arroyo FJ, Jimenez ML, Delgado Av. Influence of double-layer overlap on the electrophoretic mobility and DC conductivity of a concentrated suspension of spherical particles. J. Phys. Chem. B 2003 107 3199-3206. 

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