Definition for Isoelectric focusing
From Biology Forums Dictionary
Isoelectric focusing (IEF) is an electrophoretic technique for the separation of proteins based on their isoelectric point (pI). The pI is the pH at which a protein has no net charge and thus, does not migrate further in an electric field. IEF Gels are used to determine the isoelectric point (pI) of a protein and to detect minor changes in the protein due to post-translational modifications such as phosphorylation and glycosylation.
In Isoelectric Focusing (IEF), proteins are applied to polyacrylamide gels (IEF gels) or immobilized pH gradient (IPG) strips containing a fixed pH gradient. An electrical field is applied and the protein sample containing a mixture of proteins migrates through the pH gradient. Individual proteins are immobilized in the pH gradient as they approach their specific pI. After staining the gel and documenting the results, proteins separated by pI can be separated by mass using 2D gel electrophoresis.
