Recombinant Human GST protein

**Background of GST-Tagged Recomcombinant Proteins**

Glutathione S-transferase (GST) is a 26-kDa enzyme originally identified in the parasitic flatworm *Schistosoma japonicum*. In the 1980s, GST was adapted as a fusion tag for recombinant protein expression and purification, driven by its high-affinity binding to glutathione, a tripeptide antioxidant. This property led to the development of the GST gene fusion system, a cornerstone of affinity chromatography.

The GST tag serves dual purposes: it enhances solubility and stability of recombinant proteins during expression in bacterial (e.g., *E. coli*) or eukaryotic systems, while enabling rapid purification via glutathione-coated beads. The system, pioneered by Smith and Johnson in 1988. involves cloning a target gene into a GST-fusion vector (e.g., pGEX). Upon expression, the GST-tagged protein binds to immobilized glutathione matrices under mild conditions. Impurities are washed away, and the purified fusion protein is eluted using reduced glutathione or enzymatic cleavage.

GST-tagged proteins are widely used in pull-down assays, protein-protein interaction studies, and antibody production. The tag’s large size can sometimes interfere with protein function, necessitating tag removal via proteases like thrombin or PreScission. Despite the emergence of smaller tags (e.g., His-tag), GST remains popular due to its efficient purification, compatibility with diverse expression systems, and utility in immobilizing proteins for interaction screens or drug discovery.

Today, GST fusion technology is a staple in structural biology, proteomics, and biotechnology, balancing simplicity, cost-effectiveness, and versatility for routine or large-scale protein production.