What is "isoelectric focusing"

n. (context biochemistry English) The electrophoresis of proteins through a pH gradient to locations corresponding to their isoelectric points

Isoelectric focusing (IEF), also known as electrofocusing, is a technique for separating different molecules by differences in their isoelectric point (pI). It is a type of zone electrophoresis, usually performed on proteins in a gel, that takes advantage of the fact that overall charge on the molecule of interest is a function of the pH of its surroundings.