This is a working overview of GSSG, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-09-24. Anything still debated is marked as such rather than presented as settled.
In its reduced form, glutathione carries a sulfhydryl group that can donate electrons. This property lets it act as a major cellular antioxidant and redox buffer. Glutathione peroxidase uses it to reduce hydrogen peroxide and lipid peroxides, while glutathione reductase regenerates the reduced form using NADPH. The ratio of reduced glutathione to glutathione disulfide is widely used as an indicator of oxidative stress, though the ratio changes with compartment, cell type, and sample handling. Oxidized glutathione can also form mixed disulfides with proteins, affecting their activity.
Glutathione supports detoxification by conjugating reactive electrophiles through glutathione S-transferases. The resulting conjugates are processed and exported, often after further metabolism. It also stores cysteine, transports amino acids across membranes through the gamma-glutamyl cycle, and assists in the maturation of iron-sulfur clusters and some prostaglandins. In plants, animals, and many microbes, the molecule appears in similar roles, but concentrations vary enormously between tissues. Liver, kidney, and red blood cells tend to contain high amounts, while blood plasma contains much less.
Glutathione is a small tripeptide made of glutamic acid, cysteine, and glycine. Its cysteine thiol group allows reversible oxidation and reduction, making it central to cellular redox chemistry. The reduced form, often abbreviated GSH, predominates inside most cells, while the oxidized disulfide form, GSSG, forms when two GSH molecules react. The ratio of GSH to GSSG is widely used as an indicator of oxidative stress in laboratory research, though it does not by itself diagnose a clinical condition.
Biosynthesis occurs in two ATP-dependent steps. The enzyme glutamate-cysteine ligase joins glutamate and cysteine, forming gamma-glutamylcysteine; glutathione synthetase then adds glycine to produce the complete tripeptide. Because the peptide bond from glutamate uses the gamma-carboxyl group, glutathione resists digestion by many ordinary peptidases. Tissues vary in synthesis capacity, and the liver generally contains high concentrations relative to many other organs. This uneven distribution contributes to organ-specific differences in redox buffering and affects how experimental results are interpreted across tissue types.
Glutathione participates in detoxification reactions, amino acid transport, and the maintenance of protein thiols. It serves as a cofactor for several enzymes, including glutathione peroxidases and glutathione S-transferases. In research literature, altered glutathione status appears in studies of aging, infection, metabolic stress, and environmental exposure. Whether low glutathione is a cause, consequence, or marker of such conditions often remains unresolved. Direct measurement in blood or tissue provides a snapshot, but results depend on sample handling, timing, and the method used.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C10H17N3O6S | Refers to the reduced form |
| Molar mass | 307.32 g/mol | Calculated for the neutral molecule |
| Appearance | White crystalline powder | Often hygroscopic; protect from moisture |
| Water solubility | Soluble in water | Reported values vary with purity and form |
| Alternative names | GSH, reduced glutathione | GSH specifies the thiol form |
Glutathione is a small tripeptide built from glutamic acid, cysteine, and glycine. Its peptide bond between glutamate and cysteine involves the gamma-carboxyl group rather than the usual alpha-carboxyl group. This structure gives the molecule a reactive thiol on the cysteine residue. The reduced form, often abbreviated GSH, is the predominant intracellular species in many cell types. Because the thiol can donate electrons, glutathione participates in redox chemistry and in the conjugation of reactive molecules.
Cells synthesize glutathione through two ATP-dependent steps: glutamate-cysteine ligase joins glutamate and cysteine, and glutathione synthetase adds glycine to form the complete tripeptide. Breakdown occurs through gamma-glutamyl transpeptidase and subsequent peptidase reactions, forming the gamma-glutamyl cycle. Within cells, glutathione also forms a disulfide-linked dimer called GSSG when two GSH molecules react. The balance between GSH and GSSG is widely used as an indicator of oxidative conditions, although the ratio can vary by compartment and tissue.
Glutathione supports several cellular processes beyond direct antioxidant action. It serves as a cofactor for glutathione peroxidase and glutathione S-transferase enzymes, which reduce peroxides and conjugate electrophiles, respectively. The molecule also acts as a reservoir of cysteine, an amino acid that can limit protein synthesis and redox signaling. In human nutrition, oral glutathione is sold as a supplement, but how much intact glutathione reaches tissues after ingestion remains an active research question. Clinical claims about supplementation are not uniformly supported by controlled trials.
Glutathione synthesis proceeds in two ATP-dependent steps catalyzed by glutamate-cysteine ligase and glutathione synthetase. The first step joins glutamate and cysteine to form gamma-glutamylcysteine and is generally rate-limiting. The second step adds glycine to complete the tripeptide. Cysteine availability, feedback inhibition by glutathione, and oxidative conditions influence flux through this pathway. The pathway is conserved across many organisms, and degradation by gamma-glutamyl transpeptidase and related peptidases recycles amino acids for new synthesis.
Within cells, glutathione serves as a cofactor for glutathione peroxidases and glutathione S-transferases. These enzymes reduce hydrogen peroxide and organic peroxides or conjugate electrophilic compounds to the thiol group. The resulting conjugates can be exported and processed through mercapturic acid pathways. Glutathione also contributes to protein thiol homeostasis and to recycling of other antioxidants such as ascorbate. Its precise roles vary by tissue, and many regulatory effects observed in laboratory systems remain difficult to quantify in whole organisms.
Many items denoting 'rank and prestige' were deposited in the water surrounding Flag Fen, including swords, spearheads, 'gold earrings, tiny pins and brooches'. Archaeologist Francis Pryor, who discovered the site in 1982, suggests that 'settlers often vied for social status by showing they could afford to discard valuable possessions'. There is also evidence of intentional destruction before placement, e.g. daggers broken in half placed on top of each other. Other finds included small, polished, white stones of a type not known in the area, indicating that they had been intentionally collected and transported to and placed at the site. Other artefacts found were animal bones, including horse mandibles. Horses were very valuable to the prehistoric people, since they provided a means of transport and could supplement or replace man-power. For example, they could be used to carry or pull timbers on sledges over long distances. Significance is also drawn from the discovery of the ritual deposits within thirty metres of the timber post line, and only on its southern boundary. The amount, type, and placement of deposits, which continued for more than 1,200 years, support the theory that 'at least one facet of the site' was a role as a 'religious monument'. On Northey Island many round barrows contemporary with Flag Fen were found. These seemed to be constructed over the dwellings of 'chiefs'. Mike Parker Pearson refers to this as the "Land of the Dead". There is also evidence of farming, including sheep remains, contemporary with the site.
=== Associated conditions === Women with PMOS have an increased risk of a range of metabolic, cardiovascular, reproductive and mental health conditions. The likelihood of developing metabolic disorders is about three to seven times higher than in women without PMOS. Insulin resistance is common, even in lean women with PMOS. Overweight or obese women with PMOS are at higher risk of type 2 diabetes than women without PMOS at the same BMI. Lean women with PMOS do not appear to be at higher risk of developing diabetes. Other metabolic and cardiovascular complications commonly associated with PMOS include:
EGF acts by binding with high affinity to epidermal growth factor receptor (EGFR) on the cell surface. This stimulates ligand-induced dimerization, activating the intrinsic protein-tyrosine kinase activity of the receptor (see the second diagram). The tyrosine kinase activity, in turn, initiates a signal transduction cascade that results in a variety of biochemical changes within the cell – a rise in intracellular calcium levels, increased glycolysis and protein synthesis, and increases in the expression of certain genes including the gene for EGFR – that ultimately lead to DNA synthesis and cell proliferation.
Sources: en.wikipedia.org
with the nearest-neighbor (π orbitals) hopping energy γ0 ≈ 2.8 eV and the lattice constant a ≈ 2.46 Å. The conduction and valence bands correspond to the different signs. With one pz electron per atom in this model, the valence band is fully occupied, while the conduction band is vacant. The two bands touch at the zone corners (the K point in the Brillouin zone), where there is a zero density of states but no band gap. Thus, graphene exhibits a semi-metallic (or zero-gap semiconductor) character, although this is not true for a graphene sheet rolled into a carbon nanotube due to its curvature. Two of the six Dirac points are independent, while the rest are equivalent by symmetry. Near the K-points, the energy depends linearly on the wave vector, similar to a relativistic particle. Since an elementary cell of the lattice has a basis of two atoms, the wave function has an effective 2-spinor structure. Consequently, at low energies even neglecting the true spin, electrons can be described by an equation formally equivalent to the massless Dirac equation. Hence, the electrons and holes are called Dirac fermions. This pseudo-relativistic description is restricted to the chiral limit, i.e., to vanishing rest mass M0, leading to interesting additional features:
Even seemingly docile dragons may become unpredictably aggressive, especially when the animal's territory is invaded by someone unfamiliar. In June 2001, a Komodo dragon seriously injured Phil Bronstein, the then-husband of actress Sharon Stone, when he entered its enclosure at the Los Angeles Zoo after being invited in by its keeper. Bronstein was bitten on his bare foot, as the keeper had told him to take off his white shoes and socks, which the keeper stated could potentially excite the Komodo dragon as they were the same colour as the white rats the zoo fed the dragon. Although he survived, Bronstein needed to have several tendons in his foot reattached surgically.
=== Ecologic system of soil decontamination === The Altran Foundation jury awarded the first prize 2001 to Julien Troquet, a young research engineer and founder of the start-up company Biobasic Environnement. His project consists in developing a decontamination process for soil using bioremediation. This process allows for a complete decontamination using a gentle "alternative" method, so the excavation of the site is not necessary and the ecosystem is preserved. It is five times less expensive than competing techniques and can also be used on many different types of pollution.
Sources: en.wikipedia.org
It is a tripeptide of glutamate, cysteine, and glycine. The glutamate-cysteine bond is unusual because it forms through the gamma-carboxyl group.
It reflects the balance between oxidant exposure and antioxidant capacity. The ratio is not a direct clinical diagnosis and depends on the tissue and sample method.
No. It also participates in detoxification, amino acid transport, and protein modification. Its roles vary by cell type and compartment.
GSH is the reduced form of glutathione, with a free thiol group on cysteine. GSSG is the oxidized disulfide form, created when two GSH molecules become linked. The two forms exist together, and their balance is often reported as the GSH/GSSG ratio in laboratory studies.