This is a working overview of GLP-1, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-22 and is reviewed periodically as new material appears.
Pharmacological activity arises from agonism at the glucagon-like peptide-1 receptor, a G protein-coupled receptor expressed in the pancreas, the gastrointestinal tract, and the brainstem. Receptor activation raises intracellular cyclic adenosine monophosphate and enhances insulin release in a glucose-dependent manner, an effect that diminishes when blood glucose concentration is low. Other effects include slowed gastric emptying and hypothalamic satiety signalling. These pathways are described well. Receptor desensitisation rates across tissues, relative to the endogenous hormone, are still under investigation, and reported findings differ between laboratories.
The company that developed the compound filed it as a long-acting analogue, and it gained first approval in 2017 for type 2 diabetes. Later authorisations from several regulators extended the indication to chronic weight management, and the World Health Organization added the glucagon-like peptide-1 receptor agonist drug class to its model list of essential medicines in 2023. Production uses solid-phase peptide synthesis followed by side-chain conjugation and chromatographic purification. Supply constraints and cost differences across regions are well documented. Literature on long-term outcomes continues to grow, with many trials reporting surrogate endpoints rather than hard clinical endpoints.
Reported molecular weight is approximately 4113.6 daltons for the free base, and the peptide is supplied as a lyophilized powder or in buffered liquid form depending on the intended use. It is freely soluble in water when formulated with appropriate excipients, though the unconjugated peptide shows limited stability at neutral pH over long periods. Analytical characterization typically relies on reversed-phase high-performance liquid chromatography and mass spectrometry. Purity specifications for research-grade material commonly exceed ninety-five percent by area. Isotopic and impurity profiles differ between suppliers.
Two principal therapeutic variants exist under separate regulatory filings, one indicated for glycemic control in type 2 diabetes and one for chronic weight management. Both use the same active molecule; differences lie in formulation strength, titration schedule, and labeling. Regulatory agencies in the United States and European Union approved injectable forms in 2017 and 2018 respectively. An oral tablet formulation received approval later, using a carrier molecule to enhance absorption across the gastric epithelium. Labeling differs by jurisdiction and by indication.
| Property | Value | Notes |
|---|---|---|
| Molecular class | 31-amino-acid peptide | Modified glucagon-like peptide-1 analogue |
| Molecular mass | approximately 4114 Da | Calculated for the free peptide backbone |
| Appearance | white to off-white powder | Typical of purified lyophilised peptide batches |
| Solubility class | freely soluble in water | Aqueous solubility improves at slightly alkaline pH |
| Typical storage | -20 degrees Celsius, dry, dark | Protect from repeated freeze-thaw cycles |
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.
皮下注射后吸收相对缓慢，绝对生物利用度约为百分之八十九，血药浓度峰值通常出现在给药后一到三天。与白蛋白结合使清除减慢，终末半衰期约为一百六十五小时，接近一周。连续给药约四到五周后达到稳态暴露水平。表观分布容积约为每千克零点二五升，血浆蛋白结合率超过百分之九十九。代谢以蛋白水解切割和脂肪二酸侧链的 β-氧化为主，相关产物主要经尿液与粪便排出。
序列层面的改动同时解决了两个问题，即酶解稳定性与肾脏清除速度。天然 GLP-1 在循环中的半衰期仅约两分钟，主要被二肽基肽酶-4 迅速灭活。酰化侧链与白蛋白的可逆结合形成循环储库，使分子缓慢释放并持续激活受体。这种设计思路后来被广泛用于同类长效肽的开发，属于该类药物化学改造的典型范式。
Semaglutide 是一种经结构修饰的胰高血糖素样肽-1 类似物，其主链与内源性 GLP-1(7-36) 约有百分之九十四的序列一致性。第 8 位丙氨酸被 α-氨基异丁酸取代，使二肽基肽酶-4 无法识别原有切割位点。第 34 位赖氨酸换为精氨酸，进一步降低酶解速率。第 26 位赖氨酸经间隔基连接一条含十八个碳的二酸脂肪链，该侧链赋予分子与血浆白蛋白结合的能力。
Serum protein binding dominates the pharmacokinetic profile. The attached chain associates strongly with albumin, shielding the peptide from enzymatic attack and slowing filtration by the kidney. This interaction extends the circulation half-life to roughly one week in humans, which supports weekly administration intervals. An oral version pairs the peptide with an absorption enhancer that transiently alters gastric epithelium, permitting limited uptake; bioavailability by that route is substantially lower than by injection.
Semaglutide belongs to the glucagon-like peptide-1 receptor agonist class, a group of synthetic peptides that imitate an incretin hormone released by intestinal L cells after food intake. Native GLP-1 circulates for only a few minutes because dipeptidyl peptidase-4 cleaves it rapidly. The hormone acts on pancreatic islets, the gastrointestinal tract, and several brain regions. Because the natural peptide is short-lived, development work concentrated on analogues that keep receptor activity while resisting enzymatic breakdown and renal clearance.
The semaglutide sequence is a 31-residue analogue of human GLP-1, altered at three positions relative to the parent hormone. Aminoisobutyric acid replaces alanine at position 8, arginine replaces lysine at position 34, and a lipophilic diacid is attached to lysine 26 through a short linker. These features are reported consistently in the structural literature. The position 8 substitution blocks recognition by dipeptidyl peptidase-4, while the attached chain drives strong, reversible association with a carrier protein in blood.
=== Central Function === Asprosin can also exit the bloodstream and cross the blood–brain barrier to function in the brain. The first indication that asprosin was in fact a cerebrospinal fluid (CSF) protein, in addition to being a plasma protein, was the observation of asprosin in the CSF of rats at concentrations 5- to 10-fold lower than in the plasma. Additionally, intravenously introduced asprosin showed a dramatic ability to cross the blood–brain barrier and enter the CSF. Asprosin induces appetite via activation of orexigenic AgRP neurons and deactivation of anorexigenic POMC neurons in the arcuate nucleus of the hypothalamus. Asprosin's orexigenic effects are mediated through binding to protein tyrosine phosphatase receptor delta (PTPRD). Whole body deletion of Ptprd results in reduced appetite and extreme leanness (mirroring the effects of deficient asprosin) while selective loss of Ptprd in just AgRP neurons leads to reduced appetite and protection from diet-induced obesity. A Science Advances study titled "Asprosin promotes feeding through SK channel–dependent activation of AgRP neurons" served as a strong independent replication of the original discovery that asprosin increases appetite and body weight by activating hypothalamic AgRP neurons. It confirmed both the physiological effects—elevated food intake and weight gain following asprosin administration—and the originally proposed mechanism of AgRP neuron activation.
In 2012, newly elected President Enrique Peña Nieto, from the PRI, emphasized that he did not support the involvement of armed American agents in Mexico and was only interested in training Mexican forces in counter-insurgency tactics. At the start of his term, Peña Nieto promised to de-escalate the conflict, focusing on lowering criminal violence rates, as opposed to the previous policy of attacking drug-trafficking organizations by arresting or killing the cartel leaders and intercepting their shipments. His administration's security policy was shaped by Miguel Ángel Osorio Chong (Secretary of the Interior), Jesús Murillo Karam (Attorney General), and Salvador Cienfuegos (National Defense). In the first 14 months of his administration, between December 2012 and January 2014, 23,640 people died in the conflict. During 2012 and 2013, Mexico saw the rise of grupos de autodefensa comunitaria, vigilante self-defense groups in rural communities that took up arms against criminal groups that wanted to impose dominance in their towns, entering a new phase in the Mexican drug war. This strategy, encouraged by Óscar Naranjo, one of Peña Nieto's security advisors, crumbled when autodefensas began having internal struggles and disagreements with the government, as well as infiltration and co-optation by organized crime, causing Peña Nieto's administration to distance from them.
Vincent du Vigneaud (May 18, 1901 – December 11, 1978) was an American biochemist. He was recipient of the 1955 Nobel Prize in Chemistry "for his work on biochemically important sulphur compounds, especially for the first synthesis of a polypeptide hormone," a reference to his work on the peptide hormone oxytocin.
== Mass defect == The mass defect used in nuclear physics is different from its use in mass spectrometry. In nuclear physics, the mass defect is the difference in the mass of a composite particle and the sum of the masses of its component parts. In mass spectrometry the mass defect is defined as the difference between the exact mass and the nearest integer mass. The Kendrick mass defect is the exact Kendrick mass subtracted from the nearest integer Kendrick mass. Mass defect filtering can be used to selectively detect compounds with a mass spectrometer based on their chemical composition.
Other fruits that can disperse via water are nipa palm and screw pine. Some fruits have evolved propulsive mechanisms that fling seeds substantial distances – perhaps up to 100 m (330 ft) in the case of the sandbox tree – via explosive dehiscence or other such mechanisms (see impatiens and squirting cucumber).
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== Metabolism == Glycerol is a precursor for synthesis of triacylglycerols and of phospholipids in the liver and adipose tissue. When the body uses stored fat as a source of energy, glycerol and fatty acids are released into the bloodstream. Glycerol is mainly metabolized in the liver. Glycerol injections can be used as a simple test for liver damage, as its rate of absorption by the liver is considered an accurate measure of liver health. Glycerol metabolism is reduced in both cirrhosis and fatty liver disease. Blood glycerol levels are highly elevated during diabetes, and is believed to be the cause of reduced fertility in patients who suffer from diabetes and metabolic syndrome. Blood glycerol levels in diabetic patients average three times higher than healthy controls. Direct glycerol treatment of testes has been found to cause significant long-term reduction in sperm count. Further testing on this subject was abandoned due to the unexpected results, as this was not the goal of the experiment. Circulating glycerol does not glycate proteins as do glucose or fructose, and does not lead to the formation of advanced glycation endproducts (AGEs). In some organisms, the glycerol component can enter the glycolysis pathway directly and, thus, provide energy for cellular metabolism (or, potentially, be converted to glucose through gluconeogenesis). Before glycerol can enter the pathway of glycolysis or gluconeogenesis (depending on physiological conditions), it must be converted to their intermediate glyceraldehyde 3-phosphate in the following steps:
== Antimicrobial activity == Alone, both dalfopristin and quinupristin have modest in vitro bacteriostatic activity. However, 8-16 times higher in vitro bactericidal activity is seen against many gram-positive bacteria when the two streptogramins are combined . While quinupristin/dalfopristin is effective against staphylococci and vancomycin-resistant Enterococcus faecium, in vitro studies have not demonstrated bactericidal activity against all strains and species of common gram-positive bacteria.
==== Sexist remarks ==== On several occasions throughout his third term, Lula, speaking extemporaneously, made comments which were largely regarded as sexist. In May 2024, while announcing measures for those affected by the floods in Rio Grande do Sul, he said that "a washing machine is a very important thing for women". The next day, at a ceremony for the delivery of housing units, he said he had spoken with a 27-year-old woman with 5 children, and asked "When are you going to close the gate, comrade?". At a meeting held in the Palácio do Planalto in July 2024, Lula commented on the result of a study that found that violence against women increases after football matches, concluding: "Unbelievable. If the guy is a Corinthians supporter, that's fine". At the event marking the 2 years since the January 8 attacks, he said "I am a lover of democracy, I am not even a husband, I am a lover of democracy, because, most of the time, lovers are more passionate about their lovers than about their wives". In March 2025, at a ceremony at the Palácio do Planalto, Lula said that he had appointed a "beautiful woman" as Minister of Institutional Relations to get closer to the presidents of the Senate and the Chamber. At the opening of the 29th International Construction and Architecture Fair, held in April 2025, Lula referred disparagingly to the managing director of the International Monetary Fund, Kristalina Georgieva, calling her "a little woman".
=== Global security program === The Lab's work in global security aims to reduce and mitigate the dangers posed by the spread or use of weapons of mass destruction and by threats to energy and environmental security. Livermore has been working on global security and homeland security for decades, predating both the collapse of the Soviet Union in 1991 and the September 11, 2001, terrorist attacks. LLNL staff have been heavily involved in the cooperative nonproliferation programs with Russia to secure at-risk weapons materials and assist former weapons workers in developing peaceful applications and self-sustaining job opportunities for their expertise and technologies. In the mid-1990s, Lab scientists began devising improved biodetection capabilities, leading to miniaturized and autonomous instruments that can detect biothreat agents in a few minutes instead of the days to weeks previously required for DNA analysis. Livermore researchers address a spectrum of threats – radiological/nuclear, chemical, biological, explosives, and cyber. They combine physical and life sciences, engineering, computations, and analysis to develop technologies that solve real-world problems. Activities are grouped into five programs:
This version underwent another three weeks of testing to become the final release code; the game was still unfinished when Activision forced its release. Bloodlines' creative director Jason Anderson blamed Activision, saying that the publisher took the game from Troika without providing enough time to test and polish it. Conversely, Boyarsky defended Activision for supporting Troika as the project exceeded its budget and schedule. During the nearly four years of development, Anderson estimated that the team worked overtime for all but two months.
Sources: en.wikipedia.org
It is a glucagon-like peptide-1 receptor agonist, often grouped with the incretin mimetics. Its backbone is modified from the human hormone to resist enzymatic degradation and to bind albumin. These two features distinguish it from the native peptide.
No. It shares high sequence identity but carries non-natural modifications that alter its stability and clearance. The naturally occurring hormone is broken down within minutes, while the synthetic analogue circulates far longer.
Attachment to serum albumin reduces renal filtration of the peptide and shields it from enzymatic breakdown. The consequence is a much longer interval between administrations than unmodified peptides allow. The precise contribution of binding affinity to overall duration is still being quantified.
It is a modified version of the natural hormone, with three amino acid changes and a fatty acid side chain added. These edits extend its half-life from minutes to about one week. The core receptor activity is retained.