Zone Electrophoresis, Isoelectric Focusing, and Displacement Electrophoresis (Isotachophoresis) in Carrier-Free Solution
A fundamental requirement of any high-resolution electrophoresis method is efficient suppression of convection. This is generally achieved by the use of some more-or-less rigid supporting medium, the presence of which can, however, have several undesirable consequences: (1) The solute of interest is adsorbed, leading to low recoveries and (partial) loss of biological activity. (2) Cells and many other particles are too large to penetrate electrophoretically the channels of the supporting medium. (3) In general, the course of an electrophoretic run cannot be directly followed by scanning procedures, which makes it difficult to decide if and when a steady state has been achieved in isoelectric focusing or displacement electrophoresis. (4) Meaningful electrokinetic characterization of the solutes (e.g. by mobility measurements) cannot be made, owing to different kinds of interaction with the supporting medium. (5) The reproducibility of the electrophoresis patterns can be poor unless one can exactly reproduce the supporting beds. (6) A precipitate formed during electrophoresis can clog the pores of the supporting medium. Precipitation occurs often in steady-state electrophoresis, i.e., isoelectric focusing and displacement electrophoresis. In the absence of a support, a precipitate is not in general disturbing, since it often migrates with the same velocity as the nonaggregated solute.
KeywordsErythrocyte Membrane Supporting Medium Histidine Decarboxylase Normal Human Plasma Carrier Ampholyte
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