1.  His-Tag (Polyhistidine Tag): 

          ● Description: Consists of a string of six or more histidine residues. 

          ● Purification Method: Immobilized metal affinity chromatography (IMAC) using Ni²⁺ or Co²⁺ resins. 

          ● Advantages: Simple and effective, can be used under denaturing conditions. 

2.  GST-Tag (Glutathione S-Transferase Tag): 

          ● Description: A 26 kDa protein that binds to glutathione. 

          ● Purification Method: Affinity chromatography using glutathione-agarose resin. 

          ● Advantages: Enhances solubility of target proteins, can be used for protein-protein interaction studies. 

3.  MBP-Tag (Maltose Binding Protein Tag): 

           ● Description: A 42.5 kDa protein that binds to maltose. 

           ● Purification Method: Affinity chromatography using amylose resin. 

           ● Advantages: Increases solubility of target proteins, useful for difficult-to-express proteins. 

4.  FLAG-Tag: 

           ● Description: An eight-amino-acid sequence (DYKDDDDK). 

           ● Purification Method: Affinity chromatography using anti-FLAG antibodies or M1/M2 resin. 

           ● Advantages: Highly specific, small size minimally affects protein function. 

5.  Strep-Tag: 

           ● Description: An eight-amino-acid sequence (WSHPQFEK). 

           ● Purification Method: Affinity chromatography using Strep-Tactin or streptavidin resin.  

           ● Advantages: High purity, mild elution conditions. 

6.  CBP-Tag (Calmodulin Binding Peptide Tag): 

           ● Description: A short peptide that binds to calmodulin in the presence of calcium. 

           ● Purification Method: Affinity chromatography using calmodulin resin. 

           ● Advantages: Specific elution with EGTA, gentle purification process. 

The choice of purification method and tag depends on the nature of the target protein, the expression system used, and the downstream applications. 

GenCefe provide one-stop solutions from codon optimization, gene synthesis, to protein expression and purification. In addition to four conventional expression systems of bacterial, yeast,insect cell, and mammalian cell, we have also developed a patented cell free expression technology, which is suitable for the production of difficult proteins such as toxic proteins and membrane proteins.