Differential electrophoretic mobility

Separation by differential electrophoretic mobilities, charge state, and Stokes radii of peptides chromatographic interaction of peptides with the stationary phase both chromatographic interactions and electrophoretic mobility of the peptides... 

Capillary zone electrophoresis (CZE), also known as free-solution CE, is the most widely used mode of CE essentially because of its versatility. Protein separation in CZE is based on the differential electrophoretic mobility of the analytes. This mobility is primarily dependent on a protein s size and net charge, the charge-to-mass ratio. Solvent properties that influence the size and charge of a protein include pH, ionic strength, viscosity, and dielectric constant.67 Manipulation of these properties, most notably pH, dictates the selectivity in CZE. Maximizing the charge difference between two proteins via pH modification optimizes their separation. 

Assays that exploit the differential electrophoretic mobility of protein-DNA complexes and free DNA are called gel-shift or electrophoretic-mobility-shift assays. In these expert-... 

It is apparent from the above sections that the understanding of electrophoretic mobility involves both the phenomena of fluid flow as discussed in Chapter 4 and the double-layer potential as discussed in Chapter 11. In both places we see that theoretical results are dependent on the geometry chosen to describe the boundary conditions of the system under consideration. This continues to be true in discussing electrophoresis, for which these two topics are combined. As was the case in Chapters 4 and 11, solutions to the various differential equations that arise are possible only for rather simple geometries, of which the sphere is preeminent. 

Case 2. The chromatographic retention factors and the M/c of X and Y in this case are identical. Since their electrophoretic mobilities and MCe are different, there MCec will be different too and the two components can be separated in CEC, e.g., components B and C have the same chromatographic retention factors, but different electrophoretic mobilities. Hence, they are separated by virtue of differential electrophoretic migration as illustrated in Fig. 1.12. 

Additional substances (buffer additives) are often added to the buffer solution to alter selectivity and/or to improve efficiency, and the wall of the capillary may be treated to reduce adsorptive interactions with solute species. Organic solvents, surfactants, urea and chiral selectors are among the many additives that have been recommended (table 4-24). Many alter or even reverse the EOF by affecting the surface charge on the capillary wall, whilst some help to solubilize hydrophobic solutes, form ion-pairs, or minimize solute adsorption on the capillary wall. Chiral selectors enable racemic mixtures to be separated by differential interactions with the two enantiomers which affects their electrophoretic mobilities. Deactivation of the capillary wall to improve efficiency by minimizing internet ions. with solute species can be achieved by permanent chemical modification such as silylaytion or the... 

As previously mentioned, electrophoretic separations using open-tube capillaries are based on solute differential mobility, which is a function of charge and molecular size. A different approach is required for separating neutral or uncharged compounds. Because charge is absent, electrophoretic mobility is zero. Electro-osmotic flow would allow them to migrate, but their velocities would be equal. Separation would not be possible with the above method. 

Criteria that have been used to differentiate the isoenzymes and other multiple forms of ALP include (1) electrophoretic mobility (2) stability to denaturation by heat or chemicals (3) response to the presence of selected inhibitors (4) affinity for specific lectins and (5) immunochemical characteristics. ... 

Figure 11. Adsorption of DTAB onto precipitated silica at 298 K and different ionic strengths (a) isotherms of adsorption (b) differential molar enthalpies of displacement (c) electrophoretic mobilities of silica particles.

Saifer, A., and Corey, H., Electrophoretic mobility-ion strength studies of proteins species differentiation of cross reacting albumins. J. Biol. Chem. 217, 23-30 (1955). 

---