Purification Based on Charge Differences

Englard, S., and Seifter, S. (1990). Precipitation Techniques, Methods Enzymol. 182 285-300. 

As far as the technical aspects are concerned, the lEC is easier than the SEC. The lEC does not require perfectly poured columns, and the sample volume can amount to a multiple of the column volume. In addition, the lEC exhibits better purification factors than the SEC (between 3 and 15, depending on protein and conditions) and concentrates the sample. The yield is also often better (between 50 and 80%). With multistep purifications, it is a good idea to have the lEC at the beginning. Afterward, you have the sample in a small volume, free of endogenous ligands or other disruptive extract components. 

Choudhary, G., and Horvath, C. (1996). Ion-exchange Chromatography, Methods Enzymol. 270 47-82. 

Harvey, A., and Karlsson, E. (1980). Dendrotoxin from the Venom of the Green Mamba, Dendroaspis angusti-ceps Naunyn-Schmiedebergs Arch. Pharmacol. 312 1-6. 

For preparative lEF, the Rotofor cell (Bio-Rad) can be used. Here, a column is used for focusing. Convection streams are inhibited by a row of inserted filters and the rotation of the column around the horizontal axis. The Rotofor cell was developed by Egen et al. 1984. 

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