Recombinant tagged purification is a widely used method for purifying proteins of interest based on well-developed recombinant DNA and protein expression where the engineered protein now contains a tag.  This basis for affinity purification is known as immobilized metal affinity chromatography (IMAC) for the purification of his-tagged proteins.  GST Antibody columns may be used to purify Glutathione-S-transferase (GST) tagged proteins.  Streptavidin columns may be used to purify biotin tagged proteins and DNA.