Immobilized metal affinity chromatography (IMAC) is a powerful technique that can be used for the efficient purification of recombinant histidine (His)-tagged proteins from a variety of expression systems. The synthesis of IMAC resins begins with the derivatization of an appropriate wide-pore base resin with metal-chelating groups, such as iminodiacetic acid (IDA) or nitrilotriacetic acid (NTA). Specific transition metal ions, usually Cu2+, Ni2+, Co2+, Ca2+, or Zn2+, then bind to the chelating groups to form an immobilized metal affinity support. IMAC resins typically exhibit high affinity and metal-dependent selectivity for His-tagged proteins as well as naturally occurring proteins that are rich in histidine, cysteine, aspartatic acid, or glutamic acid residues.
Profinity IMAC Resin is based on Bio-Rad's patented† UNOsphere™ technology. Profinity IMAC beads are 60 pm particles derivatized with IDA. This resin exhibits mechanical strength and excellent pressure-flow properties that allow protein separation at high flow rates without compromising binding capacity, recovery, or final purity of target proteins. Its ligand density has also been optimized to reduce nonspecific binding. Profinity IMAC Resin has an open pore structure, making it particularly useful for purifying proteins over a wide molecular size range, especially for purification of larger proteins.