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Glutathione: antioxidant defense and regulation of its synthesis

Published on November 1, 2007 Reviewed on June 28, 2018   40 min

A selection of talks on Biochemistry

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Glutathione, antioxidant defense and regulation of its synthesis. I'm Henry J. Forman.
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The organization of this talk begins with a description of the role of glutathione in protection of cells. The sources of oxidants and electrophiles will be described, followed by examination of the elimination of oxidants and other electrophiles that depends upon glutathione. The glutathione status of the cell can be assessed and methods will be described for that. Next, we will describe the synthesis of glutathione, beginning with the pathway for the synthesis and the regulation of the enzymes in that pathway.
0:49
What is glutathione? Glutathione which is abbreviated as GSH, GSH stands for selfhydro, is the most important small molecular antioxidant synthesized in cells. It's a tripeptide that's made from three amino acids and has an unusual amide bond between the gamma-carboxyl group of glutamate and the amino group of the cysteine. The cysteine, which has the self hydrogen, is involved in reduction and conjugation reactions. Glutathione is involved in enzyme catalyzed removal of peroxides and many xenobiotics and is involved in cell cycle regulation.
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The elimination of many xenobiotic electrophiles can be accomplished through conjugation to glutathione and excretion from the cell. The quinone menadione as shown can react with glutathione nonenzymatically to form an adduct. However, the enzymatic reaction, which is catalyzed by a glutathione S-transferase where the S stands for sulfur is much faster. Once the adduct is made to a quinone, such as menadione, that can rearrange to form a quinol, and a quinol is considered to be less toxic than the quinone. It also as a conjugate with glutathione, is excreted from the cell through proteins such as the multi-drug resistance proteins.
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Glutathione: antioxidant defense and regulation of its synthesis

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