Immobilized metal-ion affinity systems for recovery and structure–function studies of proteins at molecular, supramolecular, and cellular levels*

Immobilized metal-ion affinity (IMA) adsorption is a collective term that is used to include all kinds of adsorptions where the metal ion serves as the characteristic and most essential part of adsorption center. Of all the IMA techniques, immobilized metal-affinity chromato graphy (IMAC) has been gaining popularity as the choice of purification technique for proteins. IMAC represents a separation technique that is primarily useful for proteins with natural surface exposed-histidine residues and for recombinant proteins with engineered histidine tag. This review also gives insight into other nonchromatographic applications of IMA adsorption such as immobilized metal-ion affinity gel electrophoresis (IMAGE), immobilized metal-ion affinity capillary electrophoresis (IMACE), and immobilized metal-ion affinity partitioning (IMAP).