Microgels for Efficient Protein Purification

Immobilized metal affinity chromatography (IMAC) is the most frequently used method for the separation and purification of histidine-tagged (His-tagged) proteins.[1] In this technique, the high affinity of metal ions, such as nickel or copper, to a tag sequence of the protein of interest creates strong, yet reversible binding.[2] A major limitation of current systems is their inefficiency in purifying many recombinant proteins, particularly when present in their native state or in low concentrations in the cell lysate.[3,4] Performance deficiencies are caused in part by the clogging or destruction of matrix micropores by undissolved salts and other compounds during particle synthesis,[5] limiting the surface area accessible for binding[6,7] (Figure S1 in the Supporting Information). Low surface metal density can further impair efficiency.[8,9] To overcome these limitations, some alternative chelator complexes have been suggested, including magnetic anoparticles,[10] cobalt-based affinity resins (Talon),[11] and gels.[12] However, the efficiency of these systems have not been clearly proven to be superior to others, they are relatively expensive, and they may require longer operation times.[13]