Metal chelate affinity chromatography is a method based on the different affinity of organic compounds to ions of some metals. The concept of metal chelate affinity chromatography (MCAC) was first formulated and presented by Porath in 1975. It was based on the well-known affinity of transition metal ions, such as Zn2+, Cu2+, Ni2+, and Co2+ to histidine and cysteine in aqueous solutions (Porath et al., 1975). Initially, MCAC was used for group fractionation of natural proteins forming stable complexes with immobilized metal ions. This method has been successfully used to purify lactoferrin, interferon, nucleoside diphosphatase, alpha-1-antitrypsin, superoxide dismutase, acid protease, and many other proteins (Chaga, 2001).
In 1989, a theoretical generalization of the effect of the amino acid composition of proteins on binding to immobilized metal ions appeared. Sulkowski’s paper described the requirements for binding proteins to immobilized transition metal ions. He postulated that for binding to immobilized Ni2+ and Zn2+, the presence of two exposed vicinal histidines is necessary (Sulkowski, 1989). The Ni2+ ions mobilized by them can also bind to proteins with two histidines exposed on the surface, located in a non-vicinal position, but such a bond is much weaker.
By the end of the 80s, data was accumulated on the interaction of phosphorylated proteins with immobilized metal ions and the significance of carboxylic amino acids and tyrosine. This knowledge brought a significant contribution to the understanding of affine interaction with nickel ions and allowed the discovery new directions of MCAC. A breakthrough in the use of MCAC occurred after the pioneering work of Hochuli in 1988, in which chemical and genetic approaches to protein purification were combined for the first time. In this work, the use of the hexahistidine tag (His6) artificially introduced into the recombinant protein structure for purification on a synthesized metal chelate sorbent, Ni-NTA-sepharose was described (Hochuli et al., 1988). The possibility of artificial introduction of sequences for affinity purification into the structure of recombinant proteins using methods of recombinant DNA has opened a new milestone in biotechnology. This approach has become widely used, and today more than 50% of recombinant proteins expressed in prokaryotic cells are purified using MCAC.
Reference List
Porath, J., Carlsson, J. A. N., Olsson, I., & Belfrage, G. (1975). Metal chelate affinity chromatography, a new approach to protein fractionation. Nature, 258(5536), 598-599. Web.
Chaga, G. S. (2001). Twenty-five years of immobilized metal ion affinity chromatography: past, present and future. J. Biochem. Biophys. Methods, 49, 313-334. Web.
Hochuli, E., Bannwarth, W., Döbeli, H., Gentz, R., & Stüber, D. (1988). A genetic approach to facilitate purification of recombinant proteins with a novel metal chelate adsorbent. Bio/Technology, 6(11), 1321-1325. Web.
Sulkowski, E. (1989). The saga of IMAC and MIT. Bioessays, 10(5), 170-175. Web.