Common affinity tags of recombinant protein expression and purification

From basic research protein structure and function to the development of functional protein expression and purification process, the affinity tag has become an important and effective tool for recombinant protein purification. They not only facilitate the detection and purification of the fusion protein, and may have a beneficial effect on the physical and chemical properties of the target protein, it can increase production of recombinant proteins, soluble recombinant protein to enhance and promote the proper folding of the recombinant protein.

Widely used affinity tags

Since the mid-1970s appears fusion tag technology, affinity tags have become a purified recombinant protein very effective tool with high binding specificity, mild purification conditions, the purification step is simple, wide applicability and other significant advantages. Typically, the affinity tag is defined as an amino acid sequence of a particular biological or chemical ligands with high affinity. So far, there have been many types of different functions, versatile affinity tags (Table 1), which greatly facilitates the efficient purification of recombinant proteins.

According to their different molecular size, affinity tags can be divided into two categories: one is binding to immobilized ligand short peptide tag, such as Histag, FLAG-tag, Strep-tagⅡ; the other is to identify small molecule ligands protein tag group, such as GST, MBP, etc. According to a combination of different molecular size of the ligand affinity tags can also be divided into two categories: one is a short peptide or protein tag and small molecule ligand binding, such as binding to immobilized metal His tag binding to immobilized Valley glutathione GST-tag; the other is the protein ligand binding peptide tag, such as binding to immobilized calmodulin CBP labels.

Table 1. Affinity tags for purification of recombinant proteins

Since the mid-1970s, the affinity tag fusion occurs, a variety of peptide or protein affinity tags greatly facilitate the exogenous recombinant proteins were purified and isolated protein complex expression, protein has become a field of study is not available or lack of tools. Generally speaking, a perfect affinity label should have the following characteristics: (1) can be used to purify any expression host or expression system recombinant protein; (2) can be located anywhere on the target protein without affecting its structure; (3) increase the solubility of the target protein, to promote their proper folding, increase protein expression; (4) facilitate detection of the recombinant protein. Currently, commercially available affinity tag which already has many features, but the performance is more superior, purification effect is more remarkable affinity tags still constantly looking for and development.

In addition to the affinity tag itself, reduce purification costs, simplify the purification step, the label used in combination, simultaneous removal of the label, and expand the scale purification, are using an affinity tag fusion technology requires continuous improvement and optimization aspects. In recent years there has been a new self-splicing label polymerization, the system of PHB, the ELP system, gradually eliminating the chromatographic step in the purification processes of recombinant proteins such as recombinant proteins expressed self-purification, eliminating the need for expensive chromatography resin costs, simplify the purification operation, simple physical or chemical treatment, while achieving the dual purpose of protein purification and tag removal, direct access to the higher purity of the unlabeled target protein. These novel purified recombinant proteins were purified and effective labeling system to provide more options in the future research and development of recombinant protein purification process of protein structure and function should be more widely used.

Souce: NovoPro    2016-07-11