Purification of recombinant proteins can be regarded as the most frequent application

Purification of recombinant proteins can be regarded as the most frequent application of affinity chromatography (Melander et al. 1999). The proteins in question may have been passed through genetic modification to allow optimum selection for affinity binding. In this case, the proteins are referred to as “fusion proteins” (Mattiasson et al. 1999). Various types of tags are available for use; the most common types include “glutathione-S-transferase (GST), hexahistidine (his), and maltose-binding protein (MBP)” (Melander et al. 1999). The tags are often used in the elution process. For instance, “the GST has an affinity for glutathione which is commercially available as immobilized glutathione agarose” (Mattiasson et al. 1999). During the elution process, excess glutathione is used to displace the tagged protein.