Glutathione disulfide is a disulfide

Disulfide

In chemistry, a disulfide usually refers to the structural unit composed of a linked pair of sulfur atoms. Disulfide usually refer to a chemical compound that contains a disulfide bond, such as diphenyl disulfide, C6H5S-SC6H5....

 derived from two glutathione

Glutathione

Glutathione is a tripeptide that contains an unusual peptide linkage between the amine group of cysteine and the carboxyl group of the glutamate side-chain...

 molecules.

In living cells, glutathione disulfide is reduced into two molecules of glutathione with reducing equivalents from the coenzyme NADPH. This reaction is catalyzed by the enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 glutathione reductase

Glutathione reductase

Glutathione reductase, also known as GSR or GR, is an enzyme that reduces glutathione disulfide to the sulfhydryl form GSH, which is an important cellular antioxidant....

. Antioxidant enzymes, such as glutathione peroxidase

Glutathione peroxidase

Glutathione peroxidase is the general name of an enzyme family with peroxidase activity whose main biological role is to protect the organism from oxidative damage...

s and peroxiredoxin

Peroxiredoxin

Peroxiredoxins are a ubiquitous family of antioxidant enzymes that also control cytokine-induced peroxide levels and thereby mediate signal transduction in mammalian cells.- Classification :...

s, generate glutathione disulfide during the reduction of peroxide

Peroxide

A peroxide is a compound containing an oxygen–oxygen single bond or the peroxide anion .The O−O group is called the peroxide group or peroxo group. In contrast to oxide ions, the oxygen atoms in the peroxide ion have an oxidation state of −1.The simplest stable peroxide is hydrogen peroxide...

s such as hydrogen peroxide

Hydrogen peroxide

Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

 (H₂O₂) and organic hydroperoxide

Organic peroxide

Organic peroxides are organic compounds containing the peroxide functional group . If the R' is hydrogen, the compound is called an organic hydroperoxide. Peresters have general structure RCOOR. The O-O bond easily breaks and forms free radicals of the form RO·...

s (ROOH):

2 GSH + ROOH → GSSG + ROH + H₂O

Other enzymes, such as glutaredoxin

Glutaredoxin

Glutaredoxins are small redox enzymes of approximately one hundred amino-acid residues that use glutathione as a cofactor. Glutaredoxins are oxidized by substrates, and reduced non-enzymatically by glutathione. In contrast to thioredoxins, which are reduced by thioredoxin reductase, no...

s, generate glutathione disulfide through thiol-disulfide exchange with protein disulfide bond

Disulfide bond

In chemistry, a disulfide bond is a covalent bond, usually derived by the coupling of two thiol groups. The linkage is also called an SS-bond or disulfide bridge. The overall connectivity is therefore R-S-S-R. The terminology is widely used in biochemistry...

s or other low molecular mass compounds, such as coenzyme A

Coenzyme A

Coenzyme A is a coenzyme, notable for its role in the synthesis and oxidation of fatty acids, and the oxidation of pyruvate in the citric acid cycle. All sequenced genomes encode enzymes that use coenzyme A as a substrate, and around 4% of cellular enzymes use it as a substrate...

 disulfide or dehydroascorbic acid

Dehydroascorbic acid

Dehydroascorbic acid is an oxidized form of ascorbic acid. It is actively imported into the endoplasmic reticulum of cells via glucose transporters. It is trapped therein by reduction back to ascorbate by glutathione and other thiols. Therefore, L-dehydroascorbic acid is a vitamin C compound much...

.

2 GSH + R-S-S-R → GSSG + 2 RSH