A practical reference on deamidation: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-04-15. Anything still debated is marked as such rather than presented as settled.
Tirzepatide is a synthetic peptide built from 39 amino acid residues. Its sequence is related to human glucose-dependent insulinotropic polypeptide, with modifications that include a C-terminal extension and a C20 fatty diacid joined through a linker. Those changes raise the molecule's affinity for serum albumin, which slows renal filtration and lengthens the time it stays in circulation. The free base has an average molecular mass near 4813.5 daltons. The compound is made by solid-phase peptide synthesis followed by chromatographic purification.
At the receptor level, tirzepatide activates both the glucose-dependent insulinotropic polypeptide receptor and the glucagon-like peptide-1 receptor. Both belong to the class B family of G protein-coupled receptors and signal largely through cyclic AMP accumulation. The compound binds the two receptors with differing affinity, and the pattern of signaling at each site is described in the literature as biased rather than simply proportional to occupancy. Tissues carrying these receptors include pancreatic islets, adipose tissue, the central nervous system, and the gastrointestinal tract. The relative weight of each receptor population in producing metabolic effects continues to be studied.
Tirzepatide activates both the glucose-dependent insulinotropic polypeptide receptor and the glucagon-like peptide-1 receptor, making it a dual agonist rather than a selective agent. Engagement of the GLP-1 receptor is linked to glucose-dependent insulin release, slower gastric emptying, and reduced appetite signalling. The relative contribution of the GIP arm remains an active research question; proposed roles include improved insulin sensitivity and altered adipose tissue handling. Receptor occupancy studies suggest the molecule interacts with both targets at circulating concentrations achieved during therapy.
Development began in the 2010s, when researchers modified a GIP-based scaffold to add GLP-1 activity and then attached the fatty diacid to lengthen its half-life. Clinical evaluation proceeded through large phase 3 programmes in type 2 diabetes and in obesity, and regulators in the United States cleared the compound for type 2 diabetes in 2022 and for chronic weight management in 2023. Several cardiovascular and metabolic outcome studies are still reporting, so the picture of long-term benefit and risk is incomplete. Approvals in other regions followed on different timelines.
Tirzepatide is a synthetic peptide of 39 amino acids that carries a C20 fatty diacid side chain attached through a linker. Its molecular formula is C225H348N48O68, and its molecular weight is about 4813 daltons. The compound belongs to the incretin mimetic class and is administered by subcutaneous injection. The fatty acid chain promotes binding to serum albumin, which slows renal clearance and extends the circulation time of the molecule. It was identified during screening of sequences derived from glucose-dependent insulinotropic polypeptide.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C225H348N48O68 | 39-residue synthetic peptide |
| Average molecular mass | About 4813.5 Da | Free base form |
| Appearance | White to off-white powder | Solid after lyophilization |
| Solubility class | Freely soluble in water | Also soluble in neutral aqueous buffers |
| Typical storage | At or below -20 °C, desiccated | Protect from light and moisture |
Routine characterization of the peptide relies on reversed-phase high-performance liquid chromatography for purity assessment, usually with ultraviolet detection near 214 nanometers. Intact mass measurement by liquid chromatography coupled to mass spectrometry confirms molecular identity against a theoretical value. Sequence-level confirmation uses enzymatic digestion followed by tandem mass spectrometry, an approach known as peptide mapping. Amino acid analysis gives an independent check on composition. Circular dichroism spectra are used to estimate helical content in aqueous buffer.
Stability depends strongly on physical form. The dry powder is generally regarded as stable for extended periods when held at or below minus twenty degrees Celsius in a sealed, desiccated container. In solution, degradation pathways include deamidation of asparagine and glutamine residues, oxidation of methionine, and aggregation. Reaction rates for these pathways rise with temperature. Repeated freezing and thawing of solutions promotes aggregation, and light exposure can accelerate some oxidative changes. Buffer composition and pH influence which pathway dominates at a given temperature.
Regulatory and quality discussions place the peptide within established guidance for synthetic peptides and biologics. Forced degradation studies, in which samples are exposed to heat, acid, base, peroxide, and light, identify likely degradation products and validate the selectivity of analytical methods. Reference standards allow comparison across laboratories and production batches. Purity specifications reported in the literature usually combine chromatographic purity with mass confirmation. Which impurity thresholds are meaningful for long-term behavior is still debated, and no single universal specification has been adopted across all jurisdictions.
Solid tirzepatide is handled as a lyophilised, hygroscopic peptide powder that should be kept desiccated, protected from light, and stored frozen, typically at or below minus twenty degrees Celsius for long-term retention. Material left at ambient temperature for extended periods can take up moisture, which promotes aggregation and deamidation. Commercial liquid presentations are kept refrigerated between two and eight degrees Celsius and are not frozen. Reconstituted laboratory solutions are generally held cold and used within a short window because hydrolysis and oxidation continue slowly in solution.
Identity and purity are usually established with reversed-phase high-performance liquid chromatography for the main peak and with mass spectrometry for the observed molecular mass. Peptide mapping after enzymatic digestion confirms the primary sequence, while amino acid analysis provides a quantitative composition check. Size-exclusion chromatography and ion-exchange chromatography are used to look for aggregates and charge variants. Water content, residual solvents, and counter-ion content are measured separately, since a lyophilised powder is often reported on an as-is basis unless a correction is applied.
Research-grade material circulates through suppliers that differ widely in documentation and testing practice, so a certificate of analysis is a starting point rather than proof of quality. Independent verification typically repeats chromatographic purity and mass confirmation on the received lot, and compares results against a retained reference standard. Regulatory status varies by jurisdiction, and a substance cleared as a medicine is not interchangeable with a research chemical of the same name. Open questions include how closely non-pharmaceutical lots match approved material in impurity profile and in aggregate content.
脂肪酸侧链的存在使该肽与血浆白蛋白结合能力增强，从而延长循环半衰期，支持每周一次给药的用药间隔。白蛋白结合同时改变组织分布特征，减慢肾脏清除速度。该设计思路在多种长效肽类药物中被反复采用，属于既定的药代动力学策略。
该化合物的名称与结构由国际非专利名称体系统一维持，不同文献中出现的同义写法主要在拼写顺序或盐形式描述上不同。研究者通常通过受体结合实验、细胞内环磷酸腺苷积累测定以及动物模型来确认其双激动活性。相当一部分分子层面的细节——例如两条受体通路之间的信号交叉作用——尚处于开放问题状态。
Tirzepatide is a synthetic peptide developed as a dual agonist at the glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 receptors. Its structure is built on a GIP-derived backbone with non-natural amino acid substitutions and a fatty diacid side chain that promotes albumin binding and slows clearance. That modification supports once-weekly subcutaneous dosing. Registrational trial programs reported reductions in body weight and glycated hemoglobin alongside the drug's glycemic effects.
Both receptors are class B G protein-coupled receptors that signal largely through Gs-mediated cyclic AMP production. Activation within pancreatic islets increases glucose-dependent insulin secretion and suppresses glucagon release when glucose is elevated. Outside the pancreas, signaling in the central nervous system and gut appears to influence appetite and gastric emptying. The relative contribution of each receptor to observed clinical effects remains under investigation, and the two pathways are not simply additive in practice.
If a strut of nasal-septum cartilage proves too weak, then a rib cartilage strut can be applied to provide the adequate nasal support; afterwards, the strut is covered with onlay grafts. Absent alar cartilages can be replaced using all of the conchal cartilage from both ears; two strips, each 10 mm wide, are harvested from the antihelical fold, and then are applied as replacement alar wings. The surgeon attaches them to the anterior nasal spine, and to each side of the (pear-shaped) pyriform aperture; the remainder of the harvested conchal cartilage is applied as onlay grafts to augment the nasal tip. A nasal-tip lining defect is unusual, because of its midline location; yet, the reconstruction is with an anteriorly based septal mucosal flap that is rotated into place to provide adequate coverage and correction of the nasal lining defect. Vertical lobule division (VLD) is a common technique for nasal tip refinement, which involves the medial crural angle and the lateral crural angle. (d) Alar lobule defect The appropriate surgical management of an alar lobule defect depends upon the dimensions (length, width, depth) of the wound. Anatomically, the nasal skin and the underlying soft tissues of the alar lobule form a semi-rigid aesthetic subunit that forms the graceful curve of the alar rim, and provides unobstructed airflow through the nostrils, the anterior nares.
In October 2013, A&W opened its first new concept restaurant, A&W Burgers Chicken Floats. The new concept focuses on fresh made-to-order food and heavily emphasizes customer service. The menu features burgers made with fresh beef and a choice of toppings, hand-breaded chicken tenders, all-beef hot dogs, and several sides. The new management gave A&W a significant boost in the number of locations, with 2017 scheduled to have more openings than closures. For 2018, A&W projected an increase in its franchising operations and opening new restaurants. In April 2019, A&W returned to Singapore after a 16-year absence, its first location being at Jewel Changi Airport. In June 2019, the A&W chain started moving its headquarters to the University of Kentucky Coldstream Research Campus in 2019. A&W announced in March 2022 that it was going to withdraw from the Thai market due to economic losses. The restaurants shut down on March 20. A franchise was given to western New York in early 2023, with three locations, the first of which in Niagara Falls, set to open between May and June of that year. There are nearly 1,000 A&W Restaurants worldwide that are owned or franchised through A Great American Brand, with approximately 475 of these restaurants located in the U.S. as of October 2024. A&W rebounded its profits in the first half of 2024, emphasis on its growth is given mainly to single-brand restaurants, as well as restaurants in less conventional locations. In November 2024, the chain announced its entrance to the Milwaukee and Madison markets in Wisconsin.
Even so, they could play a significant role in the shaping of the political landscape.A 2023 poll by The Wall Street Journal and the National Opinion Research Center (NORC) at the University of Chicago found that about 23% of people adults below the age of 30 thought that having children was important, 9 percentage points below those aged 65 and above.
=== Early studies === Fourteen years after the first publication on its detection in 1973, 12-HHT was reported to stimulate fetal bovine aortic and human umbilical vein endothelial cells to metabolize arachidonic acid to prostaglandin I2 (PGI2 or prostacyclin), a powerful inhibitor of platelet activation and stimulator of vasodilation (see Prostacyclin synthase). 12-HHT did not, however, alter arachidonic acid metabolism in human platelets. Shortly thereafter, 12-HHT was reported to inhibit the chemotaxis-blocking effect of a human monocyte-derived factor on human monocytes. 12-Oxo-HT, the immediate metabolite of 12-HHT, was reported to stimulate the chemotasis of human neutrophils and to inhibit platelet aggregation responses to various agents by stimulating platelets to raise their levels of cyclic adenosine monophosphate (cAMP), an intracellular signal that serves broadly to inhibit platelet activation. These studies were largely overlooked; in 1998 and 2007 publications, for example, 12-HHT was regarded as either inactive or without significant biological activity. Nonetheless, this early work suggested that 12-HHT may serve as a contributor to monocyte- and neutrophil-based inflammatory responses, and that 12-oxo-HT may serve as a counterpoise to platelet aggregation responses elicited or promoted by TXA2.
Sources: en.wikipedia.org
While Switzerland was not officially invited, the President of the Swiss Confederation Guy Parmelin welcomed the heads of state and government of the participating countries at Geneva Airport and attended other venues. The 2026 summit was the first G7 leaders' summit attended by Japanese Prime Minister Sanae Takaichi. The 2026 summit was the final G7 summit attended by French President Emmanuel Macron and British Prime Minister Keir Starmer. The participation of Giorgia Meloni and Sanae Takaichi made it the third time two G7 female leaders were principals in the G7 summit. France invited several non-G7 countries to participate in the summit and in preparatory discussions. Brazil, India, Kenya and South Korea were included as partner countries in the Sherpa track. Macron invited Indian Prime Minister Narendra Modi and Brazilian President Luiz Inácio Lula da Silva to participate in the summit during meetings held around the AI Impact Summit in New Delhi in February 2026. Additional invitations were extended to leaders from Egypt, Qatar, Saudi Arabia, Syria, Ukraine and the United Arab Emirates. Syria had been invited to participate in a G7 summit for the first time. The invitation for Syrian president Ahmed al-Sharaa was hand-delivered to Syrian Finance Minister Mohammed Yisr Barnieh, who attended the group's financial talks in Paris, though al-Sharaa did not ultimately attend. Saudi Arabia's crown prince, Mohammed bin Salman, said that he was unable to attend the summit, citing prior commitments. South Africa was not included among the invited countries.
Hydrocodone, also known as dihydrocodeinone, is a semi-synthetic opioid used to treat pain and as a cough suppressant. It is taken by mouth. Typically, it is dispensed as the combination acetaminophen/hydrocodone or ibuprofen/hydrocodone for pain severe enough to require an opioid and in combination with homatropine methylbromide to relieve cough. It is also available by itself in a long-acting form sold under the brand name Zohydro ER, among others, to treat severe pain of a prolonged duration. Hydrocodone is a controlled drug: in the United States, it is classified as a Schedule II Controlled Substance. Common side effects include dizziness, sleepiness, nausea, and constipation. Serious side effects may include low blood pressure, seizures, QT prolongation, respiratory depression, and serotonin syndrome. Rapidly decreasing the dose may result in opioid withdrawal. Use during pregnancy or breastfeeding is generally not recommended. Hydrocodone is believed to work by activating opioid receptors, mainly in the brain and spinal cord. Hydrocodone 10 mg is equivalent to about 10 mg of morphine by mouth. Hydrocodone was patented in 1923, while the long-acting formulation was approved for medical use in the United States in 2013. It is most commonly prescribed in the United States, which consumed 99% of the worldwide supply as of 2010. In 2018, it was the 402nd most commonly prescribed medication in the United States, with more than 400,000 prescriptions. Hydrocodone is a semi-synthetic opioid, converted from codeine or less often from thebaine.
Atmospheric-pressure chemical ionization uses a solvent spray at atmospheric pressure. A spray of solvent is heated to relatively high temperatures (above 400 degrees Celsius), sprayed with high flow rates of nitrogen and the entire aerosol cloud is subjected to a corona discharge that creates ions with the evaporated solvent acting as the chemical ionization reagent gas. APCI is not as "soft" (low fragmentation) an ionization technique as ESI. Note that atmospheric pressure ionization (API) should not be used as a synonym for APCI.
Sources: en.wikipedia.org
=== World War II === From the start of World War II in 1939, German ships used the gap to break out from their bases in northern Germany (and from occupied Norway after April 1940) with a view to attacking Allied shipping convoys, but Allied blocking efforts in the North Sea and in the GIUK gap impeded such break-outs. British forces occupied the Faroe Islands in April 1940, and Iceland in May 1940; the United States took over effective control of Greenland in 1940. But the German Kriegsmarine profited greatly from the fall of France in June 1940, after which German submarines could operate from bases on the French coast. The origin of the term "gap" dates to this period, when there was a gap in air coverage known as the Mid-Atlantic gap or the "Greenland air gap". This gap was an area that land-based aircraft could not reach and where, as a result, they could not carry out their anti-submarine duties.
Furthermore, the three subunits, α, β, and γ have additional four main classes based on their primary sequence. These include Gs, Gi, Gq and G12. Type 3: Kinase-linked and related receptors (see "Receptor tyrosine kinase" and "Enzyme-linked receptor") – They are composed of an extracellular domain containing the ligand binding site and an intracellular domain, often with enzymatic-function, linked by a single transmembrane alpha helix. The insulin receptor is an example. Type 4: Nuclear receptors – While they are called nuclear receptors, many are actually located in the cytoplasm and migrate to the nucleus after binding with their ligands. They are composed of a C-terminal ligand-binding region, a core DNA-binding domain (DBD) and an N-terminal domain that contains the AF1(activation function 1) region. The core region has two zinc fingers that are responsible for recognizing the DNA sequences specific to this receptor. The N terminus interacts with other cellular transcription factors in a ligand-independent manner; and, depending on these interactions, it can modify the binding/activity of the receptor. Steroid and thyroid-hormone receptors are examples of such receptors. Membrane receptors may be isolated from cell membranes by complex extraction procedures using solvents, detergents, and/or affinity purification. The structures and actions of receptors may be studied by using biophysical methods such as X-ray crystallography, NMR, circular dichroism, and dual polarisation interferometry.
Binding curves describe the binding behavior of ligand to a protein. Curves can be characterized by their shape, sigmoidal or hyperbolic, which reflect whether or not the protein exhibits cooperative or noncooperative binding behavior respectively. Typically, the x-axis describes the concentration of ligand and the y-axis describes the fractional saturation of ligands bound to all available binding sites. The Michaelis Menten equation is usually used when determining the shape of the curve. The Michaelis Menten equation is derived based on steady-state conditions and accounts for the enzyme reactions taking place in a solution. However, when the reaction takes place while the enzyme is bound to a substrate, the kinetics play out differently. Modeling with binding curves are useful when evaluating the binding affinities of oxygen to hemoglobin and myoglobin in the blood. Hemoglobin, which has four heme groups, exhibits cooperative binding. This means that the binding of oxygen to a heme group on hemoglobin induces a favorable conformation change that allows for increased binding favorability of oxygen for the next heme groups. In these circumstances, the binding curve of hemoglobin will be sigmoidal due to its increased binding favorability for oxygen. Since myoglobin has only one heme group, it exhibits noncooperative binding which is hyperbolic on a binding curve.
Sources: en.wikipedia.org
It is a synthetic peptide and a dual agonist of two incretin receptors. It is not a small molecule, and it is not structurally related to the older single-receptor peptide agonists.
The C20 fatty diacid promotes tight binding to serum albumin. That binding reduces renal clearance and extends circulation time compared with an unmodified peptide of similar length.
It is not fully established. Studies indicate that both receptors contribute to the observed effects, but the exact split between the two signaling pathways in humans remains an open question.
It is a synthetic 39-amino-acid peptide that acts on two incretin receptors, the GIP receptor and the GLP-1 receptor. It is given by subcutaneous injection and has a circulating half-life of roughly five days. It is not a small molecule and is not absorbed usefully from the gut in conventional oral form.