Glutathione S-transferases Detoxify Endogenous and Exogenous Toxic Agents- Minireview

The biotransformation of foreign substances (xenobiotic) including drugs in the body is divided into phase I, II and III. But phase II enzymes are playing a key role in the biotransformation of endogenous compounds and xenobiotics to easily excretable forms and also the metabolic inactivation of pharmacologically active substances. The phase II enzymes can perform biotransformation through conjugation reactions. Glutathione S-transferases (GSTs) are one of the versatile detoxification enzymes among phase II enzymes, which are involved in the xenobiotic metabolism and play major role in cellular protection against oxidative stress. GSTs (EC. 2.5.2.18) are belongs to a family of multifunctional enzymes which conjugate electrophilic intermediates with the endogenous tripeptide glutathione (GSH) [1]. GSTs are ubiquitous, multitalented enzymes which catalyse the nucleophilic addition of the glutathione (Glu-Cys-Gly) to numerous hazardous xenobiotic including phase I electrophilic and carcinogenic metabolites [2]. There are cytosolic, mitochondrial and membrane associated GSTs, but detoxification is the key function of cytosolic GSTs [1]. Mammalian cytosolic GSTs are extensively studied [3].