• Cutting-edge technologies
• Most reliable partner
• Unmatched experience:>10,000 Mabs,>6000 Proteins
• Superior quality of products & services
• Unmatched speed of production
• Unmatched cost-saving
What is a GST-tag?
GST stands for Glutathione S-transferase. It is a family of eukaryotic and prokaryotic metabolic isozymes best known for their ability to catalyze the conjugation of the reduced form of glutathione (GSH) to xenobiotic substrates for the purpose of detoxification. It is typically fused to the N-terminus of a recombinant protein through recombinant DNA technology.
The peptide sequence of the GST-tag is 220 amino acids (roughly 26 KDa) in size.
Why use a GST-tag for protein expression and production?
Adding a GST-tag to a protein's N-terminus can facilitate its detection, isolation, and purification by GSH affinity resin. More importantly, since GST is highly expressed protein with excellent solubility, fusing a difficult to express protein to the GST tag sometimes can greatly enhance the recombinant protein's expression as well as it solubility.
How to Purify GST-tagged Proteins?
GST-tagged recombinant protein can be affinity purified directly from a cell culture lysate or supernatant. The GST-tagged protein binds to the GSH-column. After washing away residual impurities, bound GST-tag proteins can be eluted off the affnity column by high concentration of the GSH.
How do I cleave of the GST-tag after purification?
In some applications, it is desirable to remove the GST-tag, for example, for protein crystalization. To allow cleavage of the GST-tag, a protease cleavage site needs to be engineered between the tag and the protein. An EK cleavage site behind the GST-tag (GST-EK site-protein structure) can allow complete removal of the GST-tag and the cleavage site, leaving no additional amino acids after the specific cleavage of the GST-tag. For more information on the cleavage site and tag removal by EK and HRV-3C protease, please refer to: Enterokinase (EK), HRV-3C (human rhinovirus protease).