immobilized metal-affinity chromatography (IMAC)

IMAC is based on the interactions between a transition metal ion (Co2+, Ni2+, Cu2+, Zn2+) immobilized on a matrix and specific amino acid side chains. Histidine is the amino acid that exhibits the strongest interaction with immobilized metal ion matrices, as electron donor groups on the histidine imidazole ring readily form coordination bonds with the immobilized transition metal.

e.g. Polyhistidine-tag column