TAGZyme

The TAGZyme System has the potential of forming the backbone in a combined IMAC purification/TAGZyme strategy for the efficient production of highly purified, homogeneous protein. 

Information and manuals on the TAGZyme system are available at the Qiagen website.

SELECT HERE to see a graphic presentation of the TAGZyme system (requires Flash player).

Overview:
The TAGZyme System is an efficient and specific method for complete removal of N-terminal his-tags by use of exopeptidases. The method is based on the use of dipeptidyl aminopeptidase I (DAPase) alone or in combination with glutamine cyclotransferase (Qcyclase) and pyroglutamyl aminopeptidase (pGAPase). These enzymes all have the ability to bind to IMAC matrices through an engineered his-tag in recombinant forms.This feature has been utilised in the design of a simple process consisting of aminopeptidase cleavage and subtractive IMAC purification. The system has the potential of forming the backbone in a combined IMAC/TAGZyme strategy for the efficient production of highly purified and homogeneous recombinant proteins.

Advantages:

• Complete removal of N-terminal polyhistidine purification tags (his-tags) without the risk of proteolytic degradation of the target protein due to application of exopeptidases.
• Possibility of developing standard method for purification of pharmaceutical proteins which is scalable from R&D to production.
• Very simple method which are competitively priced.

But also:

• The method is using Ni2+/Zn2+-binding enzymes, which enables simultaneous removal of processing enzymes and residual contaminants by subtractive IMAC.
• Tag encoding sequences can be optimized for efficient protein expression.
• Short reaction times and use of mild conditions.
• The combined IMAC/TAGZyme strategy can substitute the use of MAb-affinity chromatography.

Background:
During the past few years, a number of affinity purification tag systems have been developed to facilitate and standardize purification of recombinant proteins. In these systems, a terminal polypeptide for protein tag with binding specificity suitable for affinity purification is fused to the protein of interest, most frequently to the N-terminus.

The addition of a histidine-rich peptide tag (polyhistidine tag; his-tag) to the target protein is a simple and well established approach for generating a novel binding specificity. This makes one-step purification possible when using immobilized metal affinity chromatography (IMAC). IMAC matrices hold a number of advantages including high protein binding capacity and ligand stability, low costs and the use of mild elution conditions. Furthermore, because of their chemical nature, IMAC matrices can easily be sanitized and regenerated making them suitable for large scale applications.

For some applications of the purified proteins, it is not necessary to remove the his-tag. However, when the recombinant protein is intended for structural/physiological studies or pharmaceutical use, it is important to remove the his-tag to obtain the protein with the correct amino acid sequence, thus avoiding unpredictable properties. One way of removing his-tags is by use of a chemical cleavage reagent. This method has several drawbacks, including protein-destroying conditions, and the use of toxic chemicals.

Another approach is to use endoproteases which mainly recognize specific sequences, e.g. coagulation factor Xa, thrombin, TEV protease, Prescission or enterokinase (see a recent review on affinity tags and tag removal strategies here: Arnau et al. 2006). These enzymes, however, are often ineffective because the cleavage rate is affected by the accessibility of the cleavage site and of the amino acid sequence adjacent to it. Furthermore, the use of endoproteases may result in undesirable internal cleavage of the protein due to the presence of internal non-canonical cleavage sites.

Our TAGZyme System have been developed to overcome these problems...