Purification: Difference between revisions

Immobilized metal ion affinity chromatography (IMAC) is based on the specific coordinate covalent binding of amino acids to metal ions. This technique works by allowing proteins with an affinity for metal ions to be retained in a column containing immobilized metal ions, such as cobalt, nickel, copper, and zinc. Most naturally occurring proteins do not have an affinity for metal ions and recombinant DNA techniques are used to introduce this property into a protein of interest. Typically an N- or C-terminal oligohistidine tag of 6-12 histidine residues in length is introduced into the protein sequence. In its most common form, IMAC involves binding of a His₆-tagged (or simply "His-tagged") protein to a resin charged with Ni²⁺ ions.