The short version of redox status fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-12-26. Anything still debated is marked as such rather than presented as settled.
Measuring glutathione requires attention to oxidation during sample handling, because GSH in biological samples can convert to GSSG or form mixed disulfides with proteins after collection. Acidic extraction, rapid cooling, and chelating agents are commonly used to limit such changes. Analytical methods usually distinguish free reduced glutathione, total glutathione, and protein-bound forms. Because these forms have different stability and reactivity, reported values depend heavily on the preparation protocol. No single preparation is universally suitable for every biological matrix or analytical goal.
Several techniques are used for quantification. Enzymatic recycling assays rely on glutathione reductase and a colorimetric or fluorescent readout, offering sensitivity for total glutathione. High-performance liquid chromatography can separate GSH from GSSG and other thiols, often with UV, fluorescence, or electrochemical detection. Mass spectrometry provides structural confirmation and can quantify low-abundance species when paired with separation. Each approach has trade-offs in specificity, throughput, and equipment requirements, so method selection depends on the research question and available instrumentation.
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.
| Property | Value | Notes |
|---|---|---|
| Reduced form | GSH | Main intracellular thiol |
| Oxidized form | GSSG | Disulfide dimer of two GSH molecules |
| Common separation method | Reversed-phase HPLC | Often with ion-pairing or derivatization |
| Typical detection | Fluorescence or mass spectrometry | UV detection is also used in some assays |
| Storage of standards | -20 °C or below, desiccated | Limit freeze-thaw and moisture exposure |
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.
Interpreting glutathione measurements requires attention to pre-analytical variables. The GSSG concentration in a sample can rise artificially during storage or processing, making the GSH/GSSG ratio unreliable if not controlled. Reference ranges vary by specimen type, assay, and population, so comparisons across studies are difficult. Plasma glutathione is low and sensitive to hemolysis, while whole blood reflects primarily erythrocyte content. Many studies measure total glutathione rather than the reduced and oxidized forms separately, which limits conclusions about redox status.
Accurate measurement of glutathione begins with careful sample handling. Because GSH oxidizes rapidly to GSSG, samples must be processed quickly or frozen immediately. Acid precipitation with metaphosphoric acid or perchloric acid is common; it lowers pH, precipitates proteins, and helps preserve the reduced form. Chelating agents such as EDTA can limit metal-catalyzed oxidation. For whole blood, hemolysis releases glutathione from erythrocytes, so plasma and serum values differ substantially from whole blood values.
Several analytical methods can quantify glutathione, including high-performance liquid chromatography (HPLC) with UV or fluorescence detection for separating GSH and GSSG. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) offers higher specificity and sensitivity, often detecting nanomolar concentrations. The enzymatic recycling assay, often called the Tietze method, measures total glutathione by coupling reduction of GSSG to a colorimetric or fluorometric readout. Capillary electrophoresis and electrochemical detection are also used in specialized laboratories. Each method has distinct advantages and limitations regarding throughput, cost, and susceptibility to interference.
=== Vasculitis === A link has been shown between ANCA-associated vasculitis and SNPs in the COL11A2 gene in a Genomewide Association Study. It is proposed that this association may be due to linkage disequilibrium between a SNP in the HLA-DP locus and SNPs in COL11A2. This is theorised as the SNP in the HLA molecule was found to be very strongly associated with these diseases with evidence for a single genetic association.
Polyethylene terephthalate membranes (PET membranes) Polycarbonate-permeable membranes (PC membranes) Porous polylactic glycolic acid (PLGA) Historical use of electrospinning to produce synthetic scaffolds dates back to at least the late 1980s when Simon showed that technology could be used to produce nano- and submicron-scale fibrous scaffolds from polymer solutions specifically intended for use as in vitro cell and tissue substrates. This early use of electrospun lattices for cell culture and tissue engineering showed that various cell types would adhere to and proliferate upon polycarbonate fibers. It was noted that as opposed to the flattened morphology typically seen in 2D culture, cells grown on the electrospun fibers exhibited a more rounded 3-dimensional morphology generally observed of tissues in vivo.
== Research and development == Up until about 2000, the classic paradigm of wound healing, involving stem cells restricted to organ-specific lineages, had never been seriously challenged. Since then, the notion of adult stem cells having cellular plasticity or the ability to differentiate into non-lineage cells has emerged as an alternative explanation. To be more specific, hematopoietic progenitor cells (that give rise to mature cells in the blood) may have the ability de-differentiate back into hematopoietic stem cells and/or transdifferentiate into non-lineage cells, such as fibroblasts.
Sources: en.wikipedia.org
==== European investigations ==== In 2000 a study to address the concerns regarding cardiovascular safety was requested by the EMA, and the makers agreed to perform post-marketing a long-term cardiovascular morbidity/mortality study in patients on rosiglitazone in combination with a sulfonylurea or metformin: the RECORD study. The results as published in 2009 showed non-inferiority with regard to cardiovascular events and cardiovascular death when the treatment with rosiglitazone was compared with metformin or a sulfonylurea. For myocardial infarction, there was a non-statistically significant increase in risk. In their assessment, the European regulators acknowledged weaknesses of the study, such as an unexpectedly low rate of cardiovascular events and the open-label design, which may lead to reporting bias. They found that the results were inconclusive. The European Medicines Agency recommended on 23 September 2010 that Avandia be suspended from the European market. According to a probe by the British Medical Journal in September 2010, the United Kingdom's Commission on Human Medicines recommended to the Medicines and Healthcare Products Regulatory Agency (MHRA) back in July 2010, to withdraw Avandia sale because its "risks outweigh its benefits". Additionally, the probe revealed that in 2000, members of the European panel in charge of reviewing Avandia prior to its approval had concerns about the long-term risks of the drug.
=== Metabolic manipulation === Engineering of metabolic processes have been achieved through cell-free systems. Bujara et al., for example, were able to use glycolytic network extracts, consisting of enzymes from E. coli that produced dihydroxyacetone phosphate, to analyze in real-time the metabolite concentrations while altering enzyme levels, with the result of optimal production of dihydroxyacetone phosphate. Further, Calhoun and Swartz were able to use a glycolytic intermediate to fuel a cell-free system, enabling relatively inexpensive ATP generation compared to reagent usage in phosphoenolpyruvate reactions.
Not all wavelengths of light can support photosynthesis. The photosynthetic action spectrum depends on the type of accessory pigments present. For example, in green plants, the action spectrum resembles the absorption spectrum for chlorophylls and carotenoids with absorption peaks in violet-blue and red light. In red algae, the action spectrum is blue-green light, which allows these algae to use the blue end of the spectrum to grow in the deeper waters that filter out the longer wavelengths (red light) used by above-ground green plants. The non-absorbed part of the light spectrum is what gives photosynthetic organisms their color (e.g., green plants, red algae, purple bacteria) and is the least effective for photosynthesis in the respective organisms.
== Details == ADH (vasopressin) and oxytocin are stored and released by the posterior pituitary. The anterior pituitary is an amalgam of hormone-producing glandular cells. Unlike the posterior, the neurosecretory cells in the anterior pituitary synthesize their own hormones, which are transported through the pituitary portal system. These hormones are prolactin, growth hormone, TSH, adrenocorticotropic hormone, FSH and LH. Some have targets in glands and some have direct function. Conditions related to the limbic system regulate hormone release. The thalamus may also, with pain. Many of these stimuli come from the senses. Temperature control can be found in the hypothalamus. These hormones also regulate water balance and hunger, and are associated with water balance control (ADH). Other examples:
Sources: en.wikipedia.org
In organic chemistry, an active ester is an ester functional group that is highly susceptible toward nucleophilic attack. Activation can be imparted by modifications of the acyl or the alkoxy components of a normal ester, say ethyl acetate. Typical modifications call for electronegative substituents. Active esters are employed in both synthetic and biological chemistry.
Unk is sometimes used instead of Xaa, but is less standard. Ter or * (from termination) is used in notation for mutations in proteins when a stop codon occurs. It corresponds to no amino acid at all. In addition, many nonstandard amino acids have a specific code. For example, several peptide drugs, such as Bortezomib and MG132, are artificially synthesized and retain their protecting groups, which have specific codes. Bortezomib is Pyz–Phe–boroLeu, and MG132 is Z–Leu–Leu–Leu–al. To aid in the analysis of protein structure, photo-reactive amino acid analogs are available. These include photoleucine (pLeu) and photomethionine (pMet).
== History == Around 1900, surgeons tried injecting paraffin into the lips without success. Liquid silicone was used for lip augmentation, starting in the early 1960s but was abandoned thirty years later due to fears about the effects of silicone on general health and long term aesthetic outcome. In about 1980, injectable bovine collagen was introduced to the cosmetic surgery market and became the standard against which other injectable fillers were measured. However, that collagen does not last very long and requires an allergy test, causing the patient to wait at least three weeks before another appointment, after which more waiting is required to see cosmetic results.
=== Autoimmune disease === Multiple autoimmune disorders are caused by the binding of IgG to self antigens. Since FcRn extends IgG half-life in the circulation, it can also confer long half-lives on these pathogenic antibodies and promote autoimmune disease.
=== Economics === In the United States, as of 2015, the cost is between US$1,284 and US$1,386 per 30 mcg vial. As of 2020, the National Average Drug Acquisition Cost (NADAC) in the United States for Avonex was $6,872.94 for a 30 mcg kit. Avonex and Rebif are on the top ten best-selling multiple sclerosis drugs of 2013. It is an example of a specialty drug that would only be available through a specialty pharmacy. This is because it requires a refrigerated chain of distribution and costs $17,000 a year.
Sources: en.wikipedia.org
Common methods include enzymatic recycling assays, liquid chromatography, and mass spectrometry. Many protocols separate reduced glutathione from its oxidized disulfide form before detection.
The ratio compares reduced glutathione with its oxidized dimer. It is used as an indicator of redox status, although the value depends strongly on sample handling and analytical method.
Glutathione can oxidize quickly after a sample is collected. Acidification, cooling, and chelators are often used to reduce artifactual changes before analysis.
It is a tripeptide of glutamic acid, cysteine, and glycine. The linkage between glutamate and cysteine uses the gamma-carboxyl group, which is unusual for peptides.