Protein yield and ease of purification are two important criteria in choosing a system for the expression/ purification of recombinant proteins. The IMPACT (Intein Mediated Purification with an Affinity Chitin- binding Tag) T7 System from New England BioLabs, Inc., enables the purification of recombinant fusion proteins in a single chromatographic step. A major advantage of the IMPACT system is that a self-cleavage reaction is used to release the affinity tag from the protein of interest. Thus, proteases are not required to separate the target protein from the affinity tag. In other commercially available expression/purification systems, the use of proteases necessitates additional purification steps and can also be associated with other difficulties (such as cleavage at secondary sites).
Schematic illustration of the IMPACT T7 purification system. Source: Copyright 1996/97 New England BioLabs Catalog. Reprinted with permission.