Glutathione S-transferase 

Glutathione S-transferases (GSTs) are a diverse group of phase II drug metabolizing enzymes whose shared function is the conjugation of glutathione (GSH) to various electrophilic endo- and xenobiotics. GSTs have been implicated in the conjugation of endogenously produced oxidized metabolites including propenal, 4-hydroxynonenals, organic hydroperoxides, phospholipids, and fatty acid peroxides.

On the basis of subcellular localization, the GST enzymes are grouped into three different classes namely, membrane-bound microsomal, mitochondrial and cytoplasmic. The leading and most diverse group of GSTs are the cytosolic enzyme spresent in humans. These are known as phase II detoxification enzymes that comprise of at least 8 classes of isoenzymes: alpha (A), kappa (K), mu (M), omega (O), pi (P), sigma (S), theta (T), and zeta (Z). In addition, four different classes of this superfamily, called beta (β), delta(δ), phi (Φ) and tau (τ) are also present in bacteria, insects and plants.

GSTs have emerged as a promising therapeutic target because specific isozymes are overexpressed in a wide variety of tumors and may play a role in the etiology of other diseases, including neurodegenerative diseases, multiple sclerosis, and asthma.