Isoelectric point (pI)

Definition

The isoelectric point (pI) is the pH at which an amino acid or a peptide has no net electric charge. At this pH, the molecule does not move in an electric field during electrophoresis.

Related terms

Amino Acids:

Organic compounds that serve as the building blocks for proteins, containing both amino (-NH2) and carboxyl (-COOH) functional groups.

Henderson:

Hasselbalch Equation - An equation used to calculate pH as a measure of acidity in biological and chemical systems, based on the concentration of acid and its conjugate base.

Electrophoresis:

A laboratory technique used to separate charged molecules, like DNA or proteins, based on their size and charge by applying an electric field