Glutathione S-Transferase Enzyme

A Glutathione S-Transferase Enzyme is an Enzymes that utilizes Glutathione in reactions contributing to the Transformation of a wide range of compounds, including Carcinogens, Therapeutic Drugs, and products of Oxidative Stress and enzyme plays a key role in the Detoxification of such substances.

AKA: GST, Glutathione S-Transferase.
Context:
- GSTs catalyse the conjugation of reduced Glutathione — via a Sulfhydryl group — to Electrophilic Centers.
- It is a member of the Glutathione S-Transferase Enzyme Family.
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Example(s):
- Pseudomonas aeruginosa http://www.uniprot.org/uniprot/Q9I370
- PMID 4960932: “In this study we show that AK secreted by the pathogenic strains of Pseudomonas aeruginosa appears to play an important role in macrophage cell death. We purified and characterized AK from the growth medium of a cystic fibrosis isolate strain of P. aeruginosa 8821 and hyperproduced it as a fusion protein with glutathione S-transferase”
See: Human Liver.

References

(Wikipedia, 2009) ⇒ http://en.wikipedia.org/wiki/Glutathione_S-transferase
- Enzymes of the glutathione S-transferase (GST) family are composed of many cytosolic, mitochondrial, and microsomal proteins. GSTs catalyse a variety of reactions and accept endogenous and xenobiotic substrates. They are members of MAPEG family of transmembrane proteins.
- GSTs can constitute up to 10% of cytosolic protein in some mammalian organs. [1] GSTs catalyse the conjugation of reduced glutathione — via a sulfhydryl group — to electrophilic centers on a wide variety of substrates. [2] This activity detoxifies endogenous compounds such as peroxidised lipids [3], as well as breakdown of xenobiotics. GSTs may also bind toxins and function as transport proteins, and, therefore, an early term for GSTs was “ligandin”[4].
- The mammalian GST super-family consists of cytosolic dimeric isoenzymes of 45–55 kDa size that have been assigned to at least four classes: Alpha, Mu, Pi and Theta. [5] Most mammalian isoenzymes have affinity for the substrate 1-chloro-2, 4-dinitrobenzene (CDNB), and spectrophotometric assays utilising this substrate are commonly used to report GST activity[6]. However, some endogenous compounds, e.g., bilirubin, can inhibit the activity of GSTs. In mammals, GST isoforms have cell specific distributions (e.g., alpha GST in hepatocytes and pi GST in the biliary tract of the human liver). [7]