Affinity tag / Affinity tail - Biotechnology Definitions (A)

An affinity tag or affinity tail is an amino acid sequence added to a protein to facilitate purification by affinity chromatography. Affinity tags are appended to proteins so that they can be purified from their crude biological source using an affinity technique. These include chitin binding protein (CBP), maltose binding protein (MBP), and glutathione-S-transferase (GST). The poly(His) tag is a widely-used protein tag; it binds to metal matrices.