Glutathione S-transferases (GSTs) depicts a superfamily of enzymes involved in the metabolism of endogenous compounds and xenobiotics in many life forms. These enzymes protect cells against toxicants by conjugating them to glutathione, thereby neutralizing their electrophilic sites, and rendering them more water-soluble. The glutathione conjugates are metabolized further to mercapturic acid and then excreted. GSTs are also involved in the biosynthesis of eicosanoids. The catalytic mechanism of these enzymes is through binding to reduced glutathione and the electrophilic substrate to allow the nucleophilic attack of the thiol group of the glutathione to the substrate. In insects these enzymes are principally involved in the metabolism of insecticides.
Glutathione s-transferases represent an important and diverse superfamily of enzymes involved in the metabolism of endogenous and xenobiotics in virtually all living organisms. Their initial discovery in rat liver in 1961(Booth et al., 1961; Combes et al., 1961) sparked a great interest in these enzymes, which lead to their isolation and characterization in virtually all organisms. Most of the research on GSTs has been centered on human, because of their role in drug metabolism and involvement on metabolic diseases. Likewise in insects GSTs have gained much of attention for their role in pesticide metabolism leading to resistance. Progresses made in molecular biology in the recent years have enabled the sequencing of many species, revealing the structure and diversity of GST enzymes. They play a central role in the detoxification of both endogenous and xenobiotic compounds and are also involved in intracellular transport, biosynthesis of hormones and protection against oxidative stress (Hayes and Pulford 1995).
- Classification and Nomenclature
- Function of GST enzymes
- GSTs enzymes in the phase II detoxification pathway