What is isoelectric point?

The isoelectric point (pI) is the pH at which a molecule or a protein carries a net charge of zero. It is the point at which the molecule or protein is electrically neutral and isoelectric.

The isoelectric point is an important parameter for proteins as it can affect their solubility, stability, and interactions with other molecules. Proteins tend to be least soluble at their isoelectric point because they have little charge to interact with water molecules.

The isoelectric point can be calculated based on the pKa values of the amino acid side chains in the protein sequence. It is also commonly determined experimentally by measuring the pH at which a protein migrates to the center of a pH gradient using techniques such as isoelectric focusing.

Overall, understanding the isoelectric point of a molecule or protein is important for various applications in biochemistry, biotechnology, and molecular biology.