A practical reference on deamidation: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-12-23 and is reviewed periodically as new material appears.
GLP-1 receptors are expressed on pancreatic beta cells, in the gut, and in several brain regions. Receptor activation raises cyclic AMP, enhances glucose-dependent insulin secretion, and suppresses glucagon release when blood glucose is high. Effects on gastric emptying and on hypothalamic appetite circuits reduce energy intake. Because insulin release remains glucose-dependent, the risk of hypoglycemia is low when the drug is used alone. The precise contribution of each pathway to body weight change in humans remains an area of active investigation.
Clinical studies of semaglutide generally measure glycated hemoglobin, fasting plasma glucose, body weight, and composite cardiovascular endpoints. The SUSTAIN program enrolled adults with type 2 diabetes, while the STEP program focused on obesity without diabetes. Administration follows a stepwise escalation schedule designed to limit gastrointestinal effects during the first weeks. Reported outcomes include mean percentage weight change, the proportion of participants reaching defined weight-loss thresholds, and rates of nausea, vomiting, and diarrhea. Long-term data on durability after treatment stops are still limited and remain a topic of ongoing research.
Semaglutide is a synthetic peptide analog of human glucagon-like peptide-1, developed by Novo Nordisk and first approved in 2017 for type 2 diabetes. It belongs to the incretin mimetic class, a group of agents that reproduce the glucose-dependent actions of endogenous GLP-1. The molecule was engineered to resist degradation by dipeptidyl peptidase-4 and to bind serum albumin, extending its half-life from minutes to roughly one week. Approval for chronic weight management followed in 2021, based on large cardiovascular and obesity outcome trials.
Reverse-phase high-performance liquid chromatography is the standard method for purity assessment, separating the peptide from truncated or oxidized variants. Mass spectrometry confirms molecular mass and detects modifications, while ultraviolet absorbance near 280 nanometers supports concentration measurement through tryptophan and tyrosine residues. Circular dichroism can indicate secondary structure, though the peptide is largely helical in solution, and ion-exchange chromatography resolves charge variants. Purity values above 95 percent are typical for research-grade material. Stability studies track degradation over time under defined conditions.
Lyophilized semaglutide is typically stored at temperatures between minus 20 and minus 80 degrees Celsius for long-term preservation. Short-term storage at 2 to 8 degrees Celsius is common for working aliquots. Repeated freeze-thaw cycles can degrade the peptide and are usually avoided. The molecule is hygroscopic in its solid form, so containers should remain sealed with desiccant. Solutions are less stable than powders and are generally prepared fresh. Light exposure is limited because aromatic residues can undergo photo-oxidation.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C187H291N45O59 | Peptide backbone with a C18 fatty diacid side chain |
| Molecular weight | Approximately 4113 Da | Consistent with a 31-residue peptide plus linker |
| Appearance | White to off-white powder | Lyophilized solid; hygroscopic if left open |
| Solubility class | Sparingly soluble to soluble in water | Varies with pH and ionic strength |
| Typical analytical method | Reversed-phase HPLC with UV detection | Often paired with mass spectrometry for identity |
The compound binds the GLP-1 receptor on pancreatic beta cells and other tissues, activating a G-protein signaling cascade that raises intracellular cyclic AMP. This action increases glucose-dependent insulin secretion when blood glucose is elevated, while binding also slows gastric emptying and reduces glucagon release. In the central nervous system, receptor activation in the hypothalamus and brainstem contributes to reduced appetite. The fatty acid chain binds albumin, which protects the peptide from renal filtration and enzymatic degradation. This albumin binding is central to its extended circulation time.
Native GLP-1 is degraded rapidly by dipeptidyl peptidase-4. Semaglutide resists this cleavage because alanine at position 8 is replaced by alpha-aminoisobutyric acid. A second substitution at position 34 introduces arginine, which further stabilizes the peptide. The most distinctive modification is a spacer and C18 fatty diacid attached at lysine 26, enabling strong albumin affinity. These three changes together produce a half-life measured in days rather than minutes, and the same structural logic underlies other long-acting analogs in this class.
Stability studies examine how temperature, pH, and moisture influence degradation rates over time. In aqueous solution, hydrolysis and deamidation accelerate as pH moves away from mildly acidic conditions. Light exposure and residual metal ions can also trigger oxidation of susceptible residues. Accelerated aging at elevated temperature is used to estimate shelf life, though extrapolation to room temperature carries uncertainty because individual degradation pathways do not always scale predictably.
Lyophilized semaglutide powder is typically held at minus twenty degrees Celsius for long-term storage. At that temperature, solid-state degradation reactions proceed slowly and the peptide remains intact for extended periods. Repeated freeze-thaw cycles are best avoided because they promote aggregation and can shift the proportion of monomeric peptide present. Working aliquots are often prepared so that each portion is thawed only once, and desiccant is placed inside the vial to limit moisture uptake.
Development began in the early 2010s with the goal of extending GLP-1 activity beyond the brief window achieved by native peptide infusion. The earliest approved formulation was a subcutaneous injection given once weekly. A later oral tablet pairs the peptide with an absorption enhancer, sodium N-(8-[2-hydroxybenzoyl] amino) caprylate, usually shortened to SNAC. That carrier lowers local pH and helps the peptide cross gastric tissue. Both routes deliver the same active molecule.
Semaglutide is a synthetic peptide analog of human glucagon-like peptide-1, a gut hormone released after meals. Its backbone retains the GLP-1 sequence but incorporates two substitutions that slow enzymatic breakdown by dipeptidyl peptidase-4. A short polyethylene glycol linker and a C18 fatty diacid are attached to the peptide chain, allowing the molecule to bind serum albumin and remain in circulation far longer than the native hormone. The result is a circulating half-life measured in days rather than the minutes typical of endogenous GLP-1.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 or 280 nanometres is widely used to assess purity and to resolve related impurities. Liquid chromatography coupled to mass spectrometry confirms identity through the protonated molecular ion and fragment ions formed in tandem experiments. Capillary electrophoresis and peptide mapping after enzymatic digestion supply complementary information on charge variants and modification sites. Circular dichroism and nuclear magnetic resonance can report on secondary structure in solution. Absolute quantification usually depends on an external standard, and reported purity depends on the detection wavelength and integration parameters chosen.
Lyophilised material appears as a white to off-white cake or powder that is hygroscopic, and containers are usually equilibrated to room temperature before opening to limit condensation. Dissolution is performed in water, phosphate-buffered saline, or a mildly alkaline buffer, since solubility rises above neutral pH. Gentle inversion or low-speed mixing is preferred, because vigorous vortexing can promote surface denaturation and aggregation. Complete dissolution may require several minutes, and brief sonication is sometimes applied. Passing the solution through a 0.22 micrometre membrane removes particulates but does not by itself sterilise the liquid.
Storage at minus 20 degrees Celsius or lower in a desiccated container preserves the peptide for extended periods, while working solutions are commonly held at two to eight degrees Celsius for short intervals. Light exposure and repeated freeze-thaw cycles accelerate degradation, so dividing material into single-use aliquots is generally recommended. Adsorption to glass and plastic surfaces can lower the measured concentration of dilute solutions, particularly below one milligram per millilitre. The degradation routes most often reported for GLP-1 analogues are deamidation, methionine oxidation, and backbone hydrolysis. Relative rates under specific conditions are frequently described only for individual formulations.
[D]espite massive deployment of police and other resources to implement the UN Conventions, production and consumption of, and trafficking in, prohibited substances have increased exponentially over the past 30 years, representing what can only be described as a failure, which the police and judicial authorities also recognise as such ... [T]he policy of prohibiting drugs, based on the UN Conventions of 1961, 1971 and 1988, is the true cause of the increasing damage that the production of, trafficking in, and sale and use of illegal substances are inflicting on whole sectors of society, on the economy and on public institutions, eroding the health, freedom and life of individuals. The road to repeal would be difficult. Individual nations could withdraw from the treaty under the provisions of Article 30. However, as former UN drug official Cindy Fazey notes, the convention has no termination clause, and therefore would remain in effect even if only one signatory remained. The Transnational Radical Party report noted that denunciation is the only route to changing the control regime established by the treaty:
The carpal tunnel is an anatomical compartment located at the base of the palm. Nine flexor tendons and the median nerve pass through the carpal tunnel, which is surrounded on three sides by the carpal bones that form an arch. The median nerve provides feeling or sensation to the thumb, index finger, long finger, and half of the ring finger. At the level of the wrist, the median nerve supplies the muscles at the base of the thumb that allow it to abduct, move away from the other four fingers, as well as move out of the plane of the palm. The carpal tunnel is located at the middle third of the base of the palm, bounded by the bony prominence of the scaphoid tubercle and trapezium at the base of the thumb, and the hamate hook that can be palpated along the axis of the ring finger. From the anatomical position, the carpal tunnel is bordered on the anterior surface by the transverse carpal ligament, also known as the flexor retinaculum. The flexor retinaculum is a strong, fibrous band that attaches to the pisiform and the hamulus of the hamate. The proximal boundary is the distal wrist skin crease, and the distal boundary is approximated by a line known as Kaplan's cardinal line. This line uses surface landmarks, and is drawn between the apex of the skin fold between the thumb and index finger to the palpated hamate hook.
== External links == International Chemical Safety Card 0457 NIOSH Pocket Guide to Chemical Hazards. "#0226". National Institute for Occupational Safety and Health (NIOSH). Concise International Chemical Assessment Document 31: N,N-Dimethylformamide
Fu's Subcutaneous Needle (FSN), invented by Dr. Zhonghua Fu in 1996, is a method for the treatment of myofascial pain and trigger points related to Traditional Chinese Medicine (TCM) and invented by Dr. D. Simons and Dr. Janet G. Travell. FSN does not follow the rules and principles of TCM and the chosen insertion points do not coincide with traditional acupuncture points. The similarities are limited to the distal insertion of the needle to the affected area, the needle itself being a non-injection needle, and the fact that both needles are manipulated and act on soft connective tissue. FSN abstains from the muscle and deep fascia layers and is confined to only the subcutaneous layer where collagen fibers are most abundant. As the subcutaneous layer is poorly innervated, pain is less than other needling therapies. FSN is also currently being used to treat non-musculoskeletal conditions; however more research is to be carried out to conclude its effectiveness.
===== Chitosan ===== Chitosan hemostats are topical agents composed of chitosan and its salts. Chitosan bonds with platelets and red blood cells to form a gel-like clot which seals a bleeding vessel. Unlike other hemostatic agents like kaolin, its action does not require the normal hemostatic pathway and therefore continues to function even when anticoagulants like heparin are present in the patient's body, or when the patient's hemostatic ability is impaired due to the patient being hypothermic or hypovolemic. Chitosan is used in some emergency hemostats which are designed to stop traumatic life-threatening bleeding. Their use is well established in many military and trauma units.
Sources: en.wikipedia.org
=== Other manifestations === Hiatal hernia Gastroesophageal reflux Poor gastrointestinal motility Dysautonomia Gorlin's sign (touch tongue to nose) Anal prolapse Flat feet Tracheobronchomalacia / tracheal collapse Collapsed lung (spontaneous pneumothorax) Nerve disorders (carpal tunnel syndrome, acroparesthesia, neuropathy, including small fiber neuropathy) Insensitivity to local anesthetics Dental problems including gum disease and enamel hypoplasia Platelet aggregation failure (platelets do not clump together properly) Mast cell disorders (including mast cell activation syndrome and mastocytosis) Pregnancy complications: increased pain, mild to moderate peripartum bleeding, cervical insufficiency, uterine tearing, or premature rupture of membranes Hearing loss may occur in some types There is some evidence that EDS is associated with greater than expected frequencies of neurodevelopmental disorders such as attention deficit hyperactivity disorder (ADHD) and other learning, communication and motor issues, including autism spectrum conditions and Tourette syndrome. There is some evidence that EDS is associated with greater than expected frequencies of mental health issues, including anxiety and mood disorders.
== Accolades == The Chinese Room received six BAFTA Games Awards for Everybody's Gone to the Rapture (Audio Achievement, Music and Performer) and Still Wakes the Deep (Best British Game, New Intellectual Property and Performer in a Leading Role). Other significant honors include eight G.A.N.G. Award wins for Amnesia: A Machine for Pigs, Everybody's Gone to the Rapture and So Let Us Melt, eleven wins at The Independent Game Developers' Association, five D.I.C.E. Award nominations, six Golden Joystick Award nominations. The studio has also been recognized by Apple Design Awards for Little Orpheus.
does not give credibility to the report and asserting that the Iranian regime is the only party committing war crimes in the conflict. The U.S. Central Command (CENTCOM) previously denied responsibility for the strike in Lamerd and stated it was investigating the incident in Minab.
The next day, a rescue operation was organised, with a C-54 being deployed to Faya-Largeau to support one Skyraider and one French Army Light Aviation SA 330 Puma helicopter. However, a few minutes after taking off from Faya-Largeau, the C-54 was hit by two SA-7s, and its pilot performed an emergency landing while two of the aircraft's engines were on fire. All five crew members survived, and were picked up by the Puma helicopter. The SA-7 threat effectively put an end to the ENT's operations in the Faya area. Unsupported, the town's garrison collapsed on 18 February. In the face of the Libyan-supported rebel onslaught, the Chadian president, General Félix Malloum, requested a French military intervention. The French government agreed, and thus Opération Tacaud was launched in early April. The ENT went back into action on 16 April during the FROLINAT's offensive on Salal, together with French Air Force aircraft. One of its Skyraiders was shot down by an SA-7, and its pilot was killed. Even though the ANT garrison in Salal was eventually overrun by the insurgents, the French intervention was successful in stopping the rebels' advance towards the capital, N'Djamena. It also exacerbated the dissensions between the different rebel factions. The situation culminated in late summer 1978, when Hissène Habré's faction, the Armed Forces of the North (Forces Armées du Nord or FAN), defected and joined the government's forces. In turn, Habré was appointed as Chad's prime minister by Malloum.
Sources: en.wikipedia.org
=== Public utilities === Buildings in Moscow, as in other Russian cities, are warmed by district heating. Before 2004, state unitary enterprises were responsible for producing and supplying heat to clients by operating the heating stations and distribution system of Mosgorteplo, Mosteploenergo, and Teploremontnaladka; these provided service to the heating substations in the northeastern part of the city. Clients were divided among enterprises according to location. A major reform launched in 2004 consolidated companies under MIPC, which became the municipal heat supplier. Its subsidiaries were new joint-stock companies. The city's main source of heating is Mosenergo's power station, which was reformed in 2005, when about ten subsidiaries were detached. One of the newly independent companies was the District Heating Network Company (MTK) (Russian: Московская теплосетевая компания). In 2007, the Government of Moscow bought controlling stakes in this company. "Our city" is a geoinformation portal created in 2011 under Moscow's mayor, Sergei Sobyanin, to initiate constructive dialogue between Moscow residents and the city's executive authorities. This portal is being developed by the State Public Institution "New Management Technologies", together with the Moscow Department of Information Technologies. During its 10 years of operation, more than 1.7 million users have registered for the portal; it has become effective for monitoring urban infrastructure.
An analysis of GPX1 expression in oligodendrocytes from patients with major depressive disorder and control patients showed that GPX1 levels were significantly decreased in patients with the disorder, but not in their astrocytes. Shortening of telomeres and decreased expression of telomerase were also evident in these oligodendrocytes, but not in the astrocytes in these patients. This suggests that decreased oxidative stress protection, as observed by decreased GPX1 levels, and decreased telomerase expression may help give rise to telomere shortening in patients with MDD.
The drug udenafil is marketed under the trade name Zydena. It is within the PDE5 inhibitor class (which also includes avanafil, sildenafil, tadalafil, and vardenafil). Like other PDE5 inhibitors, it is used to treat erectile dysfunction. Udenafil was developed by Dong-A Pharmaceutical. It has fairly rapid onset of action (peak plasma concentration after 1 to 1.5 hours), and has long duration of action (plasma half-life of 11 to 13 hours). Udenafil's pharmacokinetics allows once-daily dosage (in addition to on-demand use). Typical doses are 100 and 200 mg. Udenafil is available in Korea, Russia, and the Philippines. It has not yet been approved for use in the United States by the U.S. Food and Drug Administration.
=== Sexual reproduction === Most species of starfish are gonochorous, with there being separate male and female individuals. Some species are simultaneous hermaphrodites, producing eggs and sperm at the same time, and in a few of these the same gonad, called an ovotestis, produces both eggs and sperm. Other starfish are sequential hermaphrodites. Protandrous individuals of species like Asterina gibbosa start life as males before changing sex into females as they grow older. In some species such as Nepanthia belcheri, a large female can split in half and the resulting offspring are males. When these grow large enough they change back into females. Each starfish arm contains two gonads that release gametes through openings called gonoducts, located on the central disc between the arms. Fertilization is generally external but in a few species, internal fertilization takes place. In most species, the buoyant eggs and sperm are simply released into the water (free spawning) and the resulting embryos and larvae live as part of the plankton. In others, the eggs may be stuck to the undersides of rocks. In certain species of starfish, the females brood their eggs – either by simply enveloping them or by holding them in specialised structures in different parts of the body, externally or internally. Those starfish that brood their eggs by "sitting" on them usually assume a humped posture with their discs raised off the substrate. Pteraster militaris broods a few of its young and disperses the remaining eggs, which are too numerous to fit into its pouch.
== Uses == Spermidine can be used in electroporation while transferring the DNA into the cell under the electrical impulse. May be used for purification of DNA-binding proteins. Spermidine is also used, along with calcium chloride, for precipitating DNA onto microprojectiles for bombardment with a gene gun. Spermidine has also been reported to protect the heart from aging and prolong the lifespan of mice, while in humans it was correlated with lower blood pressure. It also was found to reduce the amount of aging in yeast, flies, worms, and human immune cells by inducing autophagy. Spermidine may play a role in male and female fertility. Fertile men have higher spermidine levels than men who are infertile, and spermidine supplementation has been shown to help maintain a healthy hormone balance and reduce oxidative stress. Spermidine is commonly used for in vitro molecular biology reactions, particularly, in vitro transcription by phage RNA polymerases, in vitro transcription by human RNA polymerase II, and in vitro translation. Spermidine increases specificity and reproducibility of Taq-mediated PCR by neutralizing and stabilizing the negative charge on DNA phosphate backbone.
Sources: en.wikipedia.org
It is given either as a once-weekly subcutaneous injection or as an oral tablet taken once daily. The two forms use different absorption strategies, so they are not interchangeable on a milligram-for-milligram basis.
Structural modifications, including a fatty acid side chain and non-natural amino acid substitutions, slow enzymatic breakdown and promote albumin binding. These changes support once-weekly dosing rather than twice-daily administration.
The pathways involving insulin, glucagon, gastric emptying, and appetite signaling are well described. How much each pathway contributes to weight reduction in a given person is not fully established.
Long-term storage is usually at minus 20 to minus 80 degrees Celsius in a sealed, desiccated container. Working aliquots can be held briefly at 2 to 8 degrees Celsius.