Isoelectric focusing in liquid-phase medium

Is an electrophoretic separation method which separates amphoteric molecules such as proteins and peptides according to their charge as defined by the pKa values of proton-accepting sites within a molecule. For proteins and peptides, these sites can be found in the free amines and carboxylic acids located at the N- and C-termini as well as on the side chains of arginine, lysine, histidine, aspartic acid, and glutamic acid residues.