This is a working overview of GSH, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-13 and is reviewed periodically as new material appears.
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.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. It occurs in nearly all living cells, with highest concentrations in liver, kidney, and red blood cells, and exists in reduced (GSH) and oxidized disulfide (GSSG) forms. The cysteine thiol group enables reversible oxidation and reduction reactions. This property makes glutathione a central participant in cellular redox balance. The balance between these forms is often used as an indicator of oxidative stress.
Glutathione functions in redox balance, detoxification, and sulfur amino acid storage. It participates in reactions that help maintain ascorbate and protein thiol status. The molecule serves as a cofactor for several enzymes, including glutathione peroxidases and glutathione S-transferases. These enzymes reduce peroxides and conjugate electrophiles, respectively. Glutathione also contributes to the metabolism of xenobiotics and to the transport of cysteine between tissues. How interorgan transport and tissue-specific regulation shape whole-body pools remains an active area of study.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. Its cysteine residue carries a thiol group, which allows the molecule to participate in reduction and oxidation reactions. The compound exists in most living cells, where the reduced form, often abbreviated GSH, is usually more abundant than the oxidized disulfide form, GSSG. Intracellular concentrations are commonly in the millimolar range, while extracellular concentrations are much lower. This uneven distribution supports its role as a major cellular redox buffer.
Cells synthesize glutathione through two ATP-dependent enzymatic steps. The first step combines glutamate and cysteine to form gamma-glutamylcysteine, catalyzed by glutamate-cysteine ligase. The second step adds glycine, producing the complete tripeptide, catalyzed by glutathione synthetase. Glutathione itself can inhibit the first enzyme, providing negative feedback when levels are high. Because cysteine is often limiting, its availability influences how quickly the pathway proceeds. These reactions occur in the cytosol, and the resulting glutathione can be distributed to other compartments.
| Property | Value | Notes |
|---|---|---|
| Common name | Glutathione | Reduced form is abbreviated GSH |
| Chemical class | Tripeptide | Composed of glutamate, cysteine, and glycine |
| Molar mass | 307.32 g/mol | For reduced glutathione |
| CAS Registry Number | 70-18-8 | For reduced L-glutathione |
| Appearance | White crystalline powder | Typical solid reference material |
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 built from glutamate, cysteine, and glycine. The peptide bond between glutamate and cysteine uses the gamma-carboxyl group, a linkage that resists ordinary peptidases. Cells make it in two ATP-dependent steps: gamma-glutamylcysteine synthetase joins glutamate and cysteine, then glutathione synthetase adds glycine. The pathway is feedback-inhibited by glutathione itself, so intracellular levels tend to stay within a narrow range. Because cysteine is often limiting, sulfur amino acid supply influences how much glutathione a cell can produce.
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 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.
In addition to drugs being specific to a certain kind of organism (bacteria, fungi, etc.), some drugs are specific to a certain genus or species of organism, and will not work on other organisms. Because of this specificity, medical microbiologists must consider the effectiveness of certain antimicrobial drugs when making recommendations. Additionally, strains of an organism may be resistant to a certain drug or class of drug, even when it is typically effective against the species. These strains, termed resistant strains, present a serious public health concern of growing importance to the medical industry as the spread of antibiotic resistance worsens. Antimicrobial resistance is an increasingly problematic issue that leads to millions of deaths every year. Adapting to the antibiotic medicine means it no longer can kill them or stop their growth. These bacterial infections can become extremely difficult to treat since the options to remove that bacterium are now slimmer. Antibiotic resistance can be caused by overuse, misuse, spontaneous resistance, and transmitted resistance. Taking antibiotics that are not prescribed to you allows naturally resistant bacteria to survive and become "superbugs." Misuse of antibiotics includes forgetting to take one or more antibiotic doses, stopping treatment too soon, or using someone else's medicine. Mutated bacteria become increasingly resistant to medicine.
== Industrial applications == Although the use of protecting groups is not preferred in industrial syntheses, they are still used in industrial contexts, e.g. sucralose (sweetener) or the Roche synthesis of oseltamivir (Tamiflu, an antiviral drug) An important example of industrial applications of protecting group theory is the synthesis of ascorbic acid (Vitamin C) à la Reichstein.
While the body can synthesize it, it is also obtained from the diet and produced industrially by chemical synthesis for use as a food additive, a nutritional supplement, and an intermediate in the manufacture of products such as the herbicide glyphosate. Glycine can fit into hydrophobic environments due to its minimal side chain.
in 1877, Russian chemists Michael and Alexander Zaytsev reported the preparation of HMB by oxidation of 2-methylpent-4-en-2-ol with chromic acid (H2CrO4); in 1880 and 1889, Schirokoff and Reformatsky (respectively) reported that the oxidative cleavage of the vicinal diol 4-methylpentane-1,2,4-triol with acidified potassium permanganate (KMnO4) yields HMB – this result is closest related to the first synthesis as cold dilute KMnO4 oxidises alkenes to vicinal cis-diols which hot acid KMnO4 further oxidises to carbonyl-containing compounds, and the diol intermediate is not obtained when hot acidic conditions are used for alkene oxidation. In other words, racemic 4-methylpentane-1,2,4-triol is a derivative of 2-methylpent-4-en-2-ol and β-hydroxy β-methylbutyric acid is a derivative of both; and, in 1892, Kondakow reported the preparation of HMB by permanganate oxidation of 3-methylbutane-1,3-diol.
=== Economics === Trastuzumab costs about US$70,000 for a full course of treatment. Australia has negotiated a lower price of A$50,000 per course of treatment. Since October 2006, trastuzumab has been made available for Australian women and men with early-stage breast cancer via the Pharmaceutical Benefits Scheme. This is estimated to cost the country over A$470 million for 4–5 years supply of the drug. Roche has agreed with Emcure in India to make an affordable version of this cancer drug available to the Indian market. Roche has changed the brand name of the drug and has re-introduced an affordable version of the same in the Indian market. The new drug named Herclon would cost approximately RS75,000 INR (US$ 870) in the Indian market. On 16 September 2014, Genentech notified hospitals in the United States that, as of October, trastuzumab could only be purchased through their selected specialty drugs distributors not through the usual general line wholesalers. By being forced to purchase through specialty pharmacies, hospitals lost rebates from the big wholesalers and the ability to negotiate cost-minus discounts with their wholesalers.
Sources: en.wikipedia.org
=== Time-reversible and stationary models === Many useful substitution models are time-reversible; in terms of the mathematics, the model does not care which sequence is the ancestor and which is the descendant so long as all other parameters (such as the number of substitutions per site that is expected between the two sequences) are held constant. When an analysis of real biological data is performed, there is generally no access to the sequences of ancestral species, only to the present-day species. However, when a model is time-reversible, which species was the ancestral species is irrelevant. Instead, the phylogenetic tree can be rooted using any of the species, re-rooted later based on new knowledge, or left unrooted. This is because there is no 'special' species, all species will eventually derive from one another with the same probability. A model is time reversible if and only if it satisfies the property (the notation is explained below)
Typhoid epidemics also broke out in the resettlement camps, which were often isolated, located far from urban areas, and lacked health facilities, sanitation, and schools. The forced relocations of blacks to the Ciskei resulted in high population densities in the homeland, a situation that persists to the present day. On several occasions, the Ciskei government imposed collective punishment on communities that opposed its rule, and people fled the Bantustan back into South Africa proper, because of the harassment and denial of government services to dissenters. In common with other Bantustans, its independence was not recognised by the international community. Sebe once claimed that the State of Israel had granted official recognition to Ciskei, but the Israeli Foreign Ministry denied this.
Growth factor receptor-bound protein 14 is a protein that in humans is encoded by the GRB14 gene. The product of this gene belongs to a small family of adapter proteins that are known to interact with a number of receptor tyrosine kinases and signaling molecules. This gene encodes a growth factor receptor-binding protein that interacts with insulin receptors and insulin-like growth-factor receptors. This protein likely has an inhibitory effect on receptor tyrosine kinase signaling and, in particular, on insulin receptor signaling. This gene may play a role in signaling pathways that regulate growth and metabolism. Transcript variants have been reported for this gene, but their full-length natures have not been determined to date.
=== Fluorometric === Fluorescence is when a molecule emits light of one wavelength after absorbing light of a different wavelength. Fluorometric assays use a difference in the fluorescence of substrate from product to measure the enzyme reaction. These assays are in general much more sensitive than spectrophotometric assays, but can suffer from interference caused by impurities and the instability of many fluorescent compounds when exposed to light. An example of these assays is again the use of the nucleotide coenzymes NADH and NADPH. Here, the reduced forms are fluorescent and the oxidised forms non-fluorescent. Oxidation reactions can therefore be followed by a decrease in fluorescence and reduction reactions by an increase. Synthetic substrates that release a fluorescent dye in an enzyme-catalyzed reaction are also available, such as 4-methylumbelliferyl-β-D-galactoside for assaying β-galactosidase or 4-methylumbelliferyl-butyrate for assaying Candida rugosa lipase.
Sources: en.wikipedia.org
GSH is the reduced thiol form, while GSSG is the disulfide-linked oxidized dimer. The GSH:GSSG ratio is used as a redox indicator, though the ratio can vary with sample handling and cell type.
Glutathione is present in many foods, including meats, poultry, fish, some vegetables, and fruits. Cooking, storage, and digestion affect the amounts available for absorption.
Yes, both enzymatic steps in glutathione synthesis consume ATP. The first step, catalyzed by glutamate-cysteine ligase, is usually rate-limiting.
Glutathione is built from three amino acids: glutamate, cysteine, and glycine. The linkage involves the gamma-carboxyl group of glutamate rather than the alpha-carboxyl group, which is unusual for peptides. This structure protects the bond from some common peptidases.