NTA and IDA: A tale of two ligands [PDF]
Immobilized metal affinity chromatography (IMAC) is a popular method for protein purification, particularly for recombinant proteins fused to a polyhistidine tag.Transition metal ions immobilized to a matrix through a chelating ligand interact with the polyhistidine tag, effectively sequestering the fused protein from a sample. Nitrilotriacetic acid (NTA) and iminodiacetic acid (IDA) are two such ligands commonly used in commercially available resins. In this application note we summarize our knowledge, from publications and in-house experiments, regarding the differences, advantages, and disadvantages of the two ligands. We present a few basic principles that should underly the purchase of a resin to optimize purification results.