A practical reference on mass spectrometry: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-06-14. Anything still debated is marked as such rather than presented as settled.
Identity and purity are checked by reversed-phase high-performance liquid chromatography, usually with ultraviolet detection near 214 nanometres, where the peptide bond absorbs. Mass spectrometry confirms the expected mass and reveals whether truncation products or adducts are present. Acid hydrolysis followed by amino acid analysis gives the residue ratio, which should approximate one alanine, one glutamate, one aspartate and one glycine. Counter-ions such as acetate or trifluoroacetate remain in the dried product and lower net peptide content, so a stated purity figure on a label does not by itself describe how much peptide a vial holds.
Regulatory treatment differs by country. No formulation of epitalon holds a marketing authorisation as a medicine in the United States or the European Union, where material sold for laboratory use is handled as a research chemical and is not intended for human consumption. In Russia, several short peptide preparations from the same institute's peptide series are registered medicinal products, and epitalon appears in that national context. Elsewhere it is frequently offered as a cosmetic ingredient, a category with lighter requirements. Advertising claims about longevity or disease prevention are restricted in most jurisdictions, which limits how sellers describe the compound.
Freeze-dried epitalon is normally kept at minus twenty degrees Celsius in a sealed, desiccated container, protected from light. Short excursions at ambient temperature during shipping are generally tolerated, but repeated warming and cooling cycles encourage moisture uptake, which shortens shelf life. Once dissolved, the peptide is far less stable than the solid: aqueous solutions are subject to hydrolysis and to deamidation at the aspartate and glutamate residues. Working solutions are therefore held refrigerated and used within days, and repeated freezing and thawing of the same vial is best avoided.
Residue composition is the property that most cleanly separates verified material from mislabelled samples. Alanine, glutamate, aspartate and glycine appear in that order from the N-terminus, and the two acidic residues sit in the middle of the chain. Because the peptide is short, it can be produced by solid-phase synthesis and characterised by mass spectrometry without ambiguity. Any reported sample whose measured mass departs substantially from 390 daltons is a different compound or a degraded mixture rather than epitalon.
Epitalon is a synthetic tetrapeptide whose four residues are alanine, glutamate, aspartate and glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9 and its monoisotopic mass is near 390.35 daltons. The peptide carries two acidic side chains, so it is neutral to negatively charged in most aqueous buffers. Published reference summaries usually list it under both spellings, epitalon and epithalon, and treat the two names as the same material.
| Property | Value | Notes |
|---|---|---|
| Storage temperature, solid | Approximately -20 C | Sealed, desiccated, protected from light |
| Typical identity method | Electrospray mass spectrometry | Protonated ion expected near 391 |
| Typical purity method | Reversed-phase HPLC | Ultraviolet detection near 214 nm |
| Common synonyms | Epithalon, epithalone, AEDG | Spelling variants appear in supplier catalogues |
| Solution stability | Days at 2-8 C | Hydrolysis and deamidation limit shelf life |
Because epitalon has no pharmacopoeial monograph, quality assessment depends on supplier documentation and independent testing. Certificates of analysis typically report a purity figure from a single chromatographic run, a measured mass and sometimes an appearance description, but methods and acceptance criteria are not harmonised across vendors. Third-party laboratories can repeat identity and purity measurements, and mismatches between labelled and measured peptide content have been described for research peptides generally. What constitutes adequate identity confirmation for a molecule of this size stays an open question, since mass agreement alone does not separate closely related sequences.
Identity testing for epitalon relies on reversed-phase high-performance liquid chromatography for purity and mass spectrometry for mass confirmation. Because the sequence contains no tryptophan or tyrosine, ultraviolet detection at 280 nanometres is insensitive, so chromatographic methods usually monitor absorbance near 214 nanometres, where the peptide backbone absorbs. Electrospray ionisation or matrix-assisted laser desorption/ionisation then checks the intact mass against the expected value near 390 daltons. Peptide mapping or amino acid analysis after acid hydrolysis can supplement these measurements, although such confirmatory work is seldom reported on commercial certificates of analysis.
The peptide is a synthetic analogue of epithalamin, a preparation extracted from bovine pineal glands. Investigators sought a short, chemically defined molecule that would reproduce some of the endocrine and gerontological observations attributed to the glandular extract. Proposed mechanisms centre on induction of telomerase activity, an effect reported in cultured human somatic cells in the early 2000s, together with influences on melatonin secretion and neuroendocrine regulation. Those mechanisms remain incompletely characterised, and the reported telomerase response has not been consistently reproduced by independent groups working in comparable systems.
Published work on this compound consists mainly of in vitro experiments, animal studies, and small clinical investigations, a substantial share of which appeared in Russian-language journals. Sample sizes are generally small, control conditions differ between studies, and several endpoints rely on markers whose clinical meaning is itself debated. Reviews of the longevity field treat the peptide as an early example of telomerase-directed research rather than an established intervention. Regulatory treatment varies by country: some jurisdictions place it under prescription controls, others treat it as a laboratory material, and importation may be restricted regardless of local status.
Epitalon is a synthetic tetrapeptide whose sequence is alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. It was developed in Russia during the 1980s and 1990s by investigators associated with the St. Petersburg Institute of Bioregulation and Gerontology, who studied short peptides as regulators of gene expression and tissue function. The alternative spelling epithalon appears interchangeably in the literature, and the two names refer to the same molecule. Outside Russia it is encountered chiefly as a research chemical rather than a licensed medicine, and it holds no approval from the United States Food and Drug Administration or the European Medicines Agency.
Identity is normally established by reversed-phase high-performance liquid chromatography combined with mass spectrometry, a pairing that separates components and confirms molecular mass at once. Purity is quoted as a percentage from the chromatogram, and figures above ninety-five percent are a frequent commercial specification. Amino acid analysis or sequencing supplies further confirmation when required. Because many short peptides behave similarly under chromatography, retention time alone does not establish sequence; the mass measurement is what separates one tetrapeptide from another, and certificates should report both.
Short peptides such as AEDG are normally supplied as a freeze-dried solid and are kept dry, cold, and shielded from light. Holding at minus twenty degrees Celsius is common for the long term, while a refrigerator suffices for brief periods before use. The material takes up moisture to some degree, so containers should stay sealed and be allowed to reach room temperature before opening, which limits condensation on the contents. Repeated warming and cooling of a single container is discouraged because it admits water and can lower the amount of intact peptide.
Several names circulate for the same molecule, including epitalon, epithalone, epithalamin tetrapeptide, and the sequence code AEDG. A CAS registry number, 307297-39-8, is commonly cited for it, though catalogue entries should be checked against supplier documentation because mislabelled records occur. In its usual form the peptide carries free amino and carboxyl termini and is neither glycosylated nor lipidated. Researchers distinguish the defined tetrapeptide from epithalamin itself, a crude pineal preparation containing many peptides that is not chemically characterised.
Material supplied for laboratory use is normally a lyophilised white to off-white powder that dissolves readily in water and in isotonic saline. Lyophilised cakes are hygroscopic and should be equilibrated to room temperature before opening to limit condensation on the solid. Solutions are typically prepared at milligram-per-millilitre concentrations and divided into single-use aliquots, because repeated freeze–thaw cycles degrade short peptides. Aqueous solutions are far less stable than the dry powder, and identity is usually verified by mass spectrometry alongside purity estimation from reversed-phase high-performance liquid chromatography.
== Composition == Royal jelly is 67% water, 12.5% protein, 11% simple sugars (monosaccharides), 6% fatty acids and 3.5% 10-hydroxy-2-decenoic acid (10-HDA). It also contains trace minerals, antibacterial and antibiotic components, pantothenic acid (vitamin B5), pyridoxine (vitamin B6) and trace amounts of vitamin C, but none of the fat-soluble vitamins: A, D, E or K.
===== MeSH D08.811.399.520 – intramolecular transferases (EC 5.4) ===== MeSH D08.811.399.520.100 – 2-acetolactate mutase MeSH D08.811.399.520.250 – chorismate mutase MeSH D08.811.399.520.250.500 – prephenate dehydratase MeSH D08.811.399.520.250.750 – prephenate dehydrogenase MeSH D08.811.399.520.625 – methylmalonyl-coa mutase MeSH D08.811.399.520.750 – phosphotransferases (phosphomutases) MeSH D08.811.399.520.750.250 – bisphosphoglycerate mutase MeSH D08.811.399.520.750.625 – phosphoglucomutase MeSH D08.811.399.520.750.700 – phosphoglycerate mutase
Following the initial sequential resonance assignment, it is usually possible to extend the assignment from the Cα and Cβ to the rest of the sidechain using experiments such as HCCH-TOCSY, which is basically a TOCSY experiment resolved in an additional carbon dimension.
LED airport fixtures currently include medium-intensity runway lights, runway centerline lights, taxiway centerline and edge lights, guidance signs, and obstruction lighting. LEDs are also used as a light source for DLP projectors, and to backlight newer LCD television (referred to as LED TV), computer monitor (including laptop) and handheld device LCDs, succeeding older CCFL-backlit LCDs although being superseded by OLED screens. RGB LEDs raise the color gamut by as much as 45%. Screens for TV and computer displays can be made thinner using LEDs for backlighting. LEDs are small, durable and need little power, so they are used in handheld devices such as flashlights. LED strobe lights or camera flashes operate at a safe, low voltage, instead of the 250+ volts commonly found in xenon flashlamp-based lighting. This is especially useful in cameras on mobile phones, where space is at a premium and bulky voltage-raising circuitry is undesirable. LEDs are used for infrared illumination in night vision uses including security cameras. A ring of LEDs around a video camera, aimed forward into a retroreflective background, allows chroma keying in video productions.
For services to Public Health in Scotland. Gerard Anthony Lemos, CMG. Non-Executive Chair, HM Prisons and Probation Service Agency Board. For Public and Voluntary Service. Zoe Ann Lewis. Principal and Chief Executive Officer, Middlesbrough College. For services to Further Education. Dr. Andrew John Mackintosh. Adviser, The Knowledge Assets Initiative. For services to Science and Technology, and to Enterprise Development. Barbara Hilary Manning. Lately Head of Payments, Banking and Shared Services, Department for Work and Pensions. For services to the Public and to the State Funeral of Her Majesty Queen Elizabeth II. Anthony McGee. Director, Ukraine Task Force, Ministry of Defence. For Public Service. Michael Messinger, LVO, QPM. Lately Chancellor, Order of St. John (England) and Deputy Chairman, St John Ambulance. For voluntary service to St John Ambulance. Colin Morrison, OBE. Founder and Chair, Boarding School Partnerships. For services to Education. Katherine Louise Mosse, OBE. Author. For services to Literature, to Women and to Charity. Ciaran Michael Murphy, KC. Senior Counsel. For services to Criminal Justice. Stuart Neil Luke Murphy. Chief Executive, English National Opera. For services to Opera. Professor Joseph Gerard Nellis. Professor of Global Economy, School of Management Cranfield University. For services to Higher Education, to Economics, to Business and to Charity. Dr. Vanessa Jane Ogden. Chief Executive Officer, Mulberry Schools Trust. For services to Education. René Olivieri. For services to the Charitable Sector. Lynn Margaret Pamment.
Sources: en.wikipedia.org
On 12 March 2018, the UK government said that a Novichok agent had been used in an attack in the English city of Salisbury on 4 March 2018 in an attempt to kill former GRU officer Sergei Skripal and his daughter Yulia. British Prime Minister Theresa May said in Parliament: "Either this was a direct action by the Russian state against our country, or the Russian government lost control of its potentially catastrophically damaging nerve agent and allowed it to get into the hands of others." On 13 March the BBC asked Vladimir Putin if Russia was "behind the poisoning of" Skripal and he answered "Get to the bottom of it first then we can discuss it" while he delegated a spokesperson to claim that "a circus show in the British parliament" was the upshot. Boris Johnson, the Foreign Secretary, refused to shake hands with Russian ambassador Alexander Yakovenko as he expressed "outrage" over the attack. On the next day, the UK expelled 23 Russian diplomats after the Russian government refused to meet the UK's deadline of midnight on 13 March 2018 to give an explanation for the use of the substance. Addressing the United Nations Security Council on 15 March, Vassily Nebenzia, the Russian envoy to the UN, responded to the British allegations by denying that Russia had ever produced or researched the agents, stating: "No scientific research or development under the title Novichok were carried out." After the attack, 21 members of the emergency services and public were checked for possible exposure, and three were hospitalised. As of 12 March, one police officer remained in hospital.
The report concluded that a final determination of the origin was unlikely without cooperation from the Chinese government, saying their prior lack of transparency "reflect[ed] in part China's government's own uncertainty about where an investigation could lead, as well as its frustration that the international community is using the issue to exert political pressure on China." Chinese foreign ministry spokesman Wang Wenbin said that the US intelligence report was "unscientific and has no credibility". On 23 May 2021, The Wall Street Journal reported that a previously undisclosed US intelligence report stated that three researchers from the Wuhan Institute of Virology became ill enough in November 2019 to seek hospital care. The report did not specify what the illness was. Officials familiar with the intelligence differed as to the strength to which it corroborates the hypothesis that the virus responsible for COVID-19 was leaked from the WIV. The WSJ report notes that it is not unusual for people in China to go to the hospital with uncomplicated influenza or common cold symptoms. Yuan Zhiming, director of the WIV's Wuhan National Biosafety Laboratory, responded in the Global Times, a Chinese state media outlet, that the "claims are groundless". Marion Koopmans, a member of the WHO study team, described the number of flu-like illnesses at the WIV in 2019 as "completely normal". Workers at the WIV must provide yearly serum samples. WIV virologist Shi Zhengli said in 2020 that, based on an evaluation of those serum samples, all staff tested negative for COVID-19 antibodies.
is the fracture stress for the bulk material. These models demonstrate that the bulk material selection can drastically impact the mechanical response of freeze casted structures under stress. Other microstructural features such as the lamellar thickness, pore morphology and degree of macroporosity can also heavily influence the compressive strength and Young's modulus of these highly anisotropic structures.
== Causes == Type 1 diabetes is caused by the destruction of β-cells—the only cells in the body that produce insulin—and the consequent progressive insulin deficiency. Without insulin, the body cannot respond effectively to increases in blood sugar. Due to this, people with untreated diabetes have persistent hyperglycemia. In 70–90% of cases, β-cells are destroyed by one's own immune system, for reasons that are not entirely clear. The best-studied components of this autoimmune response are β-cell-targeted autoantibodies that begin to develop in the months or years before symptoms arise. Typically, antibodies against insulin or the protein GAD65,are the first to develop, followed by antibodies against the proteins IA-2, IA-2β, and/or ZNT8. People with a higher level of these antibodies, especially those who develop them earlier in life, are at higher risk for developing symptomatic type 1 diabetes. The trigger for the development of these antibodies remains unclear. Several explanatory theories have been put forward, and the cause may involve genetic susceptibility, a diabetogenic trigger, and/or exposure to an antigen. The remaining 10–30% of patients with type 1 diabetes have β-cell destruction but no sign of autoimmunity; this is called idiopathic type 1 diabetes (its cause is unknown).
== Synthesis == The gene, GNRH1, for the GnRH precursor is located on chromosome 8. In mammals, the linear decapeptide end-product is synthesized from an 89-amino acid preprohormone in the preoptic anterior hypothalamus. It is the target of various regulatory mechanisms of the hypothalamic–pituitary–gonadal axis, such as being inhibited by increased estrogen levels in the body.
Sources: en.wikipedia.org
The solid is kept cold, dry and dark, typically at minus twenty degrees Celsius, in a sealed container with desiccant. Dissolved material is kept refrigerated and used promptly. Freezing and thawing a solution repeatedly is avoided because it accelerates degradation.
Reversed-phase chromatography with ultraviolet detection gives a purity percentage, while mass spectrometry confirms identity. Amino acid analysis checks the residue composition. Buyers typically request a certificate of analysis showing these measurements for the specific lot.
It is not authorised as a medicine in the United States or the European Union. Material is sold there as a research chemical or cosmetic ingredient. Some related short peptides are registered drugs in Russia, which is a distinct national situation rather than a general approval.
It is a four-amino-acid peptide built from alanine, glutamate, aspartate and glycine in that order. Its formula is C14H22N4O9, and it is made by chemical synthesis rather than extracted from tissue. The synthetic peptide is a single defined molecule, unlike the pineal extracts it is often compared with.