Characteristics of the isoelectric focusing procedure: importance of column size, pH, and protein-protein interactions

Isoelectric focusing (IEF) on 110- and 440-ml columns can result in the loss of enzyme activity. Such losses can be reduced or eliminated by focusing on 20-ml columns. Artifacts which arise during the IEF procedure may result from protein-protein interaction or from the interaction of pH with other sources of artifacts. The reasons for greater loss of activity on large columns and the mechanism of artifacts due to pH and protein-protein interactions are discussed.