glutathione comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-05-18. Where a claim depends on a specific study, the study is described rather than over-claimed.
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 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.
Quantifying glutathione requires distinguishing GSH from GSSG and preventing oxidation during sample preparation. Common approaches include the enzymatic recycling assay, often called the Tietze method, which measures total glutathione after converting GSSG to GSH. HPLC with ultraviolet or fluorescence detection and LC-MS/MS can separate and quantify both forms, sometimes after derivatization of the thiol group. Blood, plasma, and tissue samples differ in matrix and baseline concentrations, so method validation must account for recovery, linearity, and interference. No single assay is universally standard.
Glutathione is most stable as a dry powder stored cool and dry, but its thiol group is readily oxidized in solution. Aqueous preparations at neutral or alkaline pH lose GSH faster because the thiolate form reacts with dissolved oxygen and metal ions. Acidic conditions, chelating agents, and oxygen exclusion can slow oxidation, while repeated freeze-thaw cycles promote degradation. Light exposure and trace metals also contribute to loss. Laboratories typically validate stability for their own matrices because degradation rates depend on pH, temperature, concentration, and container materials.
| 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 |
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. It contains an unusual gamma-glutamyl bond between glutamate and cysteine, which resists cleavage by many peptidases. The reduced form, GSH, carries a thiol group on cysteine and is the dominant intracellular form in most cells. Its structure allows it to participate in redox reactions and to serve as a sulfur donor. The oxidized form, GSSG, consists of two GSH molecules joined by a disulfide bond.
In cells, glutathione helps maintain the reducing environment of the cytosol and supports enzymes that counteract reactive oxygen species. It acts as a cofactor for glutathione peroxidases, which reduce hydrogen peroxide and lipid peroxides, and for glutathione S-transferases, which conjugate electrophiles. The ratio of GSH to GSSG is often used as an indicator of oxidative stress, although the ratio can vary by compartment and cell type. Glutathione also stores cysteine, an amino acid that can be limiting for protein synthesis and antioxidant defense.
Glutathione is synthesized in two ATP-dependent steps. First, gamma-glutamylcysteine synthetase links glutamate and cysteine; second, glutathione synthetase adds glycine to form the complete tripeptide. The pathway is feedback-inhibited by GSH itself, which helps maintain steady intracellular levels. Tissues vary widely in glutathione content, with the liver typically containing the highest concentrations, followed by the kidneys, lungs, and erythrocytes. Because cysteine is often limiting, its availability influences synthesis rates, and regulation of this pathway varies by cell type.
Glutathione serves as a cofactor for several enzymes, including glutathione peroxidase and glutathione S-transferase. These enzymes help reduce hydrogen peroxide and lipid peroxides, and they conjugate reactive electrophiles for excretion. The molecule also acts as a reservoir for cysteine, an amino acid that is prone to oxidation. In addition, glutathione participates in the metabolism of nitric oxide, leukotrienes, and prostaglandins. Its roles extend to cell signaling, apoptosis, and the regulation of protein function through S-glutathionylation.
== Medical uses == Liraglutide is an anti-diabetic medication used for the treatment of type 2 diabetes or obesity. Liraglutide (Victoza) is indicated as an adjunct to diet and exercise to improve glycemic control in people aged ten years of age and older with type 2 diabetes; and to reduce the risk of major adverse cardiovascular events in adults with type 2 diabetes and established cardiovascular disease. Liraglutide (Saxenda) is indicated in combination with a reduced calorie diet and increased physical activity to reduce excess body weight and maintain weight reduction long term in people aged twelve years of age and older with body weight greater than 60 kilograms (130 lb) and obesity; and in adults with overweight in the presence of at least one weight-related comorbid condition.
== Risks == There are over 250 toxins and carcinogens in cigarette smoke. The risks of developing lung cancer, brain tumors, and acute myeloid leukemia and the incidence of heart disease and benign respiratory diseases increase with the inhalation of sidestream smoke. Additionally, the chance of developing breast cancer and cervical cancer also increases with the inhalation of sidestream smoke. Evidence has shown that sidestream smoke may be more harmful, per gram, than mainstream smoke. However, sidesmoke is inhaled in far lesser amounts than mainstream smoke in people who smoke tobacco. The relative risk of cardiovascular disease is 1.2–1.3 with exposure to sidestream smoke due to the cyanide present in the smoke. There is also evidence that sidestream smoke causes negative effects in children, both behaviorally and cognitively. One study found that higher levels of cotinine in children were correlated with a decreased ability to perform in reading and math. Factors such as age, gender and different occupations put a person at risk for bladder cancer - smoking is the only other known risk. 4-aminobiphenyl (4-ABP) is an integral component in tobacco smoke, as well as a risk factor for bladder cancer. Sidestream smoke puts individuals at an increased risk of bladder cancer because the 4-ABP concentrations are over ten times that of mainstream smoke.
=== Translation start sites === Using a method developed by Hunt, Shine and Dalgarno showed that the nucleotide tract at the 3' end of E. coli 16S ribosomal RNA (rRNA) (that is, the end where translation begins) is pyrimidine-rich and has the specific sequence 5'-YACCUCCUUA-3'. They proposed that these ribosomal nucleotides recognize the complementary purine-rich sequence 5'-AGGAGGU-3', which is found upstream of the start codon AUG in a number of mRNAs found in viruses that affect E. coli. Many studies have confirmed that base pairing between the Shine–Dalgarno sequence in mRNA and the 3' end of 16S rRNA is of prime importance for initiation of translation by bacterial ribosomes. Given the complementary relationship between rRNA and the Shine–Dalgarno sequence in mRNA, it was proposed that the sequence at the 3'-end of the rRNA determines the capacity of the prokaryotic ribosome to translate a particular gene in an mRNA. Base pairing between the 3'-end of the rRNA and the Shine–Dalgarno sequence in mRNA is a mechanism by which the cell can distinguish between initiator AUGs and internal and/or out-of-frame AUG sequences. The degree of base pairing also plays a role in determining the rate of initiation at different AUG initiator codons.
Sources: en.wikipedia.org
=== Brandeis (1972-2019) === In 1972, Redfield joined Brandeis University with a joint appointment in physics and biochemistry. He designed his own spectrometer and apparatus that was the first to specifically target biological systems. The apparatus was similar in design to later commercial units, but because it was housed on shelves, it was easy to change out components and calibrate in many ways. The processing software and pulse sequences were original, and pulse sequences were selected by a switch. The pulse lengths were adjusted with an analog pot for S/N and selective pulse water suppression. He had one physics postdoc and one chemistry or biochemistry postdoc in his lab. In 1979, Redfield was elected to the National Academy of Sciences, and in 1983, he was named a Fellow in the American Academy of Arts and Sciences. He was given the Max Delbrück Prize by the American Physical Society in 2006.
The Normans (Norman: Normaunds; French: Normands; Latin: Nortmanni/Normanni) were a population arising in the medieval Duchy of Normandy from the intermingling between Norse Viking settlers and locals of West Francia. The Norse settlements in West Francia followed a series of raids on the French northern coast mainly from what is now Denmark, although some also sailed from Norway and Sweden. These settlements were finally legitimized when Rollo, a Scandinavian Viking leader, agreed to swear fealty to King Charles III of West Francia following the siege of Chartres in 911, leading to the formation of the County of Rouen. This new fief, through kinship in the decades to come, would expand into what came to be known as the Duchy of Normandy. The Norse settlers, whom the region as well as its inhabitants were named after, adopted the language, religion, social customs and martial doctrine of the West Franks but their offspring nonetheless retained many of their traits, notably their mercenary tendencies and their fervour for adventures. The intermixing between Norse folk and native West Franks in Normandy produced an ethnic and cultural "Norman" identity in the first half of the 10th century, an identity which continued to evolve over the centuries. The Norman dynasty had a major political, cultural and military impact on medieval Europe and the Near East. The Normans were historically famed for their martial spirit, and eventually for their Catholic piety as adherents of the Catholic orthodoxy of the Romance community.
Glutathione peroxidase 2 is an enzyme that in humans is encoded by the GPX2 gene. This gene is a member of the glutathione peroxidase family encoding a selenium-dependent glutathione peroxidase that is one of two isoenzymes responsible for the majority of the glutathione-dependent hydrogen peroxide-reducing activity in the epithelium of the gastrointestinal tract. Studies in knockout mice indicate that mRNA expression levels respond to luminal microflora, suggesting a role of the ileal glutathione peroxidases in preventing inflammation in the GI tract. The antioxidant enzyme glutathione peroxidase 2 (Gpx2) is one out of eight known glutathione peroxidases (Gpx1-8) in humans. Mammalian Gpx1, GPx2 (this protein), Gpx3, and Gpx4 have been shown to be selenium-containing enzymes, whereas Gpx6 is a selenoprotein in humans with cysteine-containing homologues in rodents. In selenoproteins, the 21st amino acid selenocysteine is inserted in the nascent polypeptide chain during the process of translational recoding of the UGA stop codon.
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.
The ratio depends on rapid separation or blocking of GSH before oxidation occurs. GSSG can be formed ex vivo if samples are not processed quickly in cold, acidic conditions. Even small delays can shift the apparent ratio, making standardized protocols essential.