GST, 218 a.a.

The GST enzyme is a 26 kDa protein that typically functions as a dimer in aerobic organisms . Each monomer consists of two domains:

1. GSH-binding domain: This domain has an α/β structure similar to thioredoxin.
2. Hydrophobic substrate-binding domain: This domain is entirely helical .

GST enzymes are known for their ability to reduce lipid hydroperoxides through their selenium-independent glutathione peroxidase activity. They also detoxify lipid peroxidation end products such as 4-hydroxynonenal (4-HNE) .

The recombinant form of GST is produced in Escherichia coli and consists of 218 amino acids, with a molecular mass of 25.4 kDa . This recombinant protein is often used in various research applications due to its ability to form fusion proteins. The GST-fusion protein expression system allows a peptide or regulatory protein domain to be expressed as a fusion to the C-terminus of Schistosoma japonicum GST .

The GST-fusion protein system is widely used in:

• Protein purification: The fusion protein can be purified via GST-affinity column chromatography.
• Protein-protein and protein-DNA interaction studies: The fusion proteins retain GST enzymatic activity and can undergo dimerization similar to in vivo conditions .
• Crystallization and molecular immunology studies: The technique is used to generate different kinds of proteins for these studies .
• Vaccine production: The system is also employed in the production of vaccines .

The recombinant GST protein is typically stored as a sterile filtered clear solution containing PBS and 10% glycerol. For short-term storage, it is kept at 4°C, while for long-term storage, it is frozen at -20°C. It is recommended to add a carrier protein (0.1% HSA or BSA) for long-term storage to avoid multiple freeze-thaw cycles .

The specific activity of the recombinant GST is greater than 30 units/mg, defined as the amount of enzyme that conjugates 1.0 µmole of 1-chloro-2,4-dinitrobenzene (CDNB) with reduced glutathione per minute at pH 6.5 at 25°C .