A practical reference on GLP-1 类似物: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released by intestinal L cells after food intake. The natural hormone acts on pancreatic and central receptors but is degraded within minutes by dipeptidyl peptidase-4 and other peptidases. Semaglutide belongs to the class of long-acting GLP-1 receptor agonists, a group distinguished by structural changes that slow breakdown and extend circulation time. Its development followed earlier short-acting analogues and reflects a general strategy in peptide drug design: preserve receptor activity while blocking proteolytic clearance.
Three structural changes define the molecule. At position 8 an alpha-aminoisobutyric acid residue replaces alanine, which blocks dipeptidyl peptidase-4 cleavage. At position 34 arginine replaces lysine, and at position 26 a lysine carries a C18 fatty diacid attached through a short linker. The fatty chain binds serum albumin, and this albumin association reduces renal filtration and enzymatic attack. The unchanged backbone retains the receptor contacts that produce signalling. The free base has the formula C187H291N45O59 and a molecular weight near 4114 daltons.
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.
Receptor activation raises intracellular cyclic AMP through Gs coupling, which promotes glucose-dependent insulin release and suppresses glucagon secretion when blood glucose is elevated. Effects outside the pancreas include slower gastric emptying and altered appetite signalling in the hypothalamus and hindbrain. The relative contribution of each tissue to overall metabolic outcomes remains an area of active investigation. Central mechanisms in particular are inferred mainly from animal models and indirect human measures rather than direct observation.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C187H291N45O59 | free base, without counter-ion |
| Molecular weight | About 4114 Da | peptide backbone plus attached lipid chain |
| Plasma half-life | About 165 hours | supports once-weekly dosing in humans |
| Plasma protein binding | Greater than 99 percent | attributed mainly to serum albumin |
| Receptor target | GLP-1 receptor | Gs-coupled, raises intracellular cyclic AMP |
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。
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.
Identity and purity are usually assessed by reverse-phase high-performance liquid chromatography coupled to mass spectrometry. Retention time and observed mass are compared against a reference standard run under identical conditions. Impurity profiles reveal deamidation products, oxidized methionine variants, and truncated fragments that arise during synthesis or storage. Peptide mapping through enzymatic digestion confirms the primary sequence, while amino acid analysis offers an independent check on overall composition.
Chocolate manufacturers produce a range of products from chocolate bars to fudge. Large manufacturers of chocolate products include Cadbury, Ferrero, Guylian, The Hershey Company, Lindt & Sprüngli, Mars, Incorporated, Milka, Neuhaus and Suchard. Guylian is best known for its chocolate sea shells; Cadbury for its Dairy Milk and Creme Egg. The Hershey Company, the largest chocolate manufacturer in North America, produces the Hershey Bar and Hershey's Kisses. Mars Incorporated, a large privately owned U.S. corporation, produces Mars Bar, Milky Way, M&M's, Twix, and Snickers. Lindt is known for its truffle balls and gold foil-wrapped Easter bunnies. Food conglomerates Nestlé SA and Mondelēz both have chocolate brands. Nestlé acquired Rowntree's in 1988 and now markets chocolates under their brand, including Smarties (a chocolate candy) and Kit Kat (a chocolate bar); Kraft Foods through its 1990 acquisition of Jacobs Suchard, now owns Milka and Suchard. Fry's, Trebor Basset and the fair trade brand Green & Black's also belongs to the group.
Carrie Ann Inaba (singer-actress) is the US national awareness ambassador and spokesperson for the Sjögren's Foundation (previously the Sjögren's Syndrome Foundation). Venus Williams (world champion tennis player) has been diagnosed with Sjögren's disease and said she had struggled with fatigue for years. Stephen McPhail (professional soccer player for Ireland, Leeds, and Cardiff City) was diagnosed with lymphoma and Sjögren's disease at age 29. Halsey (American singer) was diagnosed with Sjogren's, Ehlers–Danlos syndrome, mast cell activation syndrome, and postural orthostatic tachycardia syndrome. Slađana Milošević (Serbian singer) died after struggling with Sjögren's disease.
=== DNA testing === After a disease-causing mutation has been identified in an index case (which is not always accomplished conclusively), the main task is genetic identification of carriers within a pedigree, a sequential process known as "cascade testing". Family members with the same mutation may show different severities of disease, a phenomenon known as "variable penetrance". As a result, some may remain asymptomatic, with little lifelong evidence of disease. Nevertheless, their children remain at risk of inheriting the disorder and potentially being more severely affected.
Sources: en.wikipedia.org
== Carcinoma in situ (230–234) == 230 Carcinoma in situ of digestive organs 231 Carcinoma in situ of respiratory system 232 Carcinoma in situ of skin 233 Carcinoma in situ of breast and genitourinary system 234 Carcinoma in situ of other and unspecified sites
: equilibrium In order to meet the thermodynamic condition for equilibrium, the Gibbs energy must be stationary, meaning that the derivative of G with respect to the extent of reaction, ξ, must be zero. It can be shown that in this case, the sum of chemical potentials times the stoichiometric coefficients of the products is equal to the sum of those corresponding to the reactants. Therefore, the sum of the Gibbs energies of the reactants must be the equal to the sum of the Gibbs energies of the products.
Dinosaurs belong to a group known as archosaurs, which also includes modern crocodilians. Within the archosaur group, dinosaurs are differentiated most noticeably by their gait. Dinosaur legs extend directly beneath the body, whereas the legs of lizards and crocodilians sprawl out to either side. Collectively, dinosaurs as a clade are divided into two primary branches, Saurischia and Ornithischia. Saurischia includes those taxa sharing a more recent common ancestor with birds than with Ornithischia, while Ornithischia includes all taxa sharing a more recent common ancestor with Triceratops than with Saurischia. Anatomically, these two groups can be distinguished most noticeably by their pelvic structure. Early saurischians—"lizard-hipped", from the Greek sauros (σαῦρος) meaning "lizard" and ischion (ἰσχίον) meaning "hip joint"—retained the hip structure of their ancestors, with a pubis bone directed cranially, or forward. This basic form was modified by rotating the pubis backward to varying degrees in several groups (Herrerasaurus, therizinosauroids, dromaeosaurids, and birds). Saurischia includes the theropods (exclusively bipedal and with a wide variety of diets) and sauropodomorphs (long-necked herbivores which include advanced, quadrupedal groups). By contrast, ornithischians—"bird-hipped", from the Greek ornis (ὀρνίς) meaning "bird" and ischion (ἰσχίον) meaning "hip joint"—had a pelvis that superficially resembled a bird's pelvis: the pubic bone was oriented caudally (rear-pointing).
=== Children and mentees === Wolverine has a number of children, most notably his daughter, Laura Kinney (X-23), and his son, Akihiro (Daken). A group of his other children, the Mongrels, were used in a plot to torture him by the Red Right Hand. Besides his biological children, Wolverine has also been a mentor and father figure to several younger women, especially Kitty Pryde and Jubilee.
Sources: en.wikipedia.org
=== Sports === Current evidence-based studies show that unusually high levels of circulating testosterone are associated with increased athletic performance in women, unless they lack androgen sensitivity. However, controversy has emerged in the form of the claim that testosterone is not unlike any other physical parameter with reference to bestowing advantages or disadvantages on female athletes. Existing regulations throughout competitive sports are currently being refined to specifically address this particular claim. Following the case of South African athlete Caster Semenya, an athlete with a difference in sex development (DSD) and internal testes, the International Association of Athletics Federations introduced its hyperandrogenism regulations, which restricted those registered as women with high testosterone levels, whether the hormones were produced by ovaries, adrenals, or testes. These regulations replaced the earlier sex verification rules. Following a series of legal challenges, regulations called the Eligibility Regulations for the Female Classification (Athletes with Differences of Sexual Development) were released on 1 May 2019. These regulations apply only to athletes who have a DSD, high testosterone and virilization, and no longer include hyperandrogenism from non-DSD-related causes such as PMOS. Such DSDs, often seen in people who have a Y chromosome and testes, include 5α‐reductase deficiency, partial androgen insensitivity, and congenital adrenal hyperplasia.
=== EC 1.1.98 With other, known, acceptors === EC 1.1.98.1: Now EC 1.1.9.1, alcohol dehydrogenase (azurin) EC 1.1.98.2: glucose-6-phosphate dehydrogenase (coenzyme-F420) EC 1.1.98.3: decaprenylphospho-β-D-ribofuranose 2-oxidase EC 1.1.98.3: decaprenylphospho-β-D-ribofuranose 2-dehydrogenase EC 1.1.98.4: F420H2:quinone oxidoreductase EC 1.1.98.5: secondary-alcohol dehydrogenase (coenzyme-F420) EC 1.1.98.6: ribonucleoside-triphosphate reductase (formate) EC 1.1.98.7: serine-type anaerobic sulfatase-maturating enzyme
In terms of reaction mechanism, SeO2 and the allylic substrate react via pericyclic process beginning with an ene reaction that activates the C−H bond. The second step is a [2,3] sigmatropic reaction. Oxidations involving selenium dioxide are often carried out with catalytic amounts of the selenium compound and in presence of a sacrificial catalyst or co-oxidant such as hydrogen peroxide. SeO2-based oxidations sometimes afford carbonyl compounds such as ketones, β-Pinene and cyclohexanone oxidation to 1,2-cyclohexanedione. Oxidation of ketones having α-methylene groups affords diketones. This type of oxidation with selenium oxide is called Riley oxidation. Aza analogues attach an amide, rather than alcohol, at the corresponding position (Ts=Tosyl):
=== Oakley et al. (2013) === In 2013 combined study of morphology, including fossils, and molecular data, including expressed sequence tag, mitochondrial genome, nuclear genome, and ribosomal DNA data, Oakley et al. obtained support for three pancrustacean clades: Oligostraca (Ostracoda, Mystacocarida, Branchiura, Pentastomida), Multicrustacea (Copepoda, Thecostraca, Malacostraca) and a clade they refer to as Allotriocarida (Branchiopoda, Cephalocarida, Remipedia, Hexapoda), as well as for monophyly of Ostracoda. Within Multicrustacea they obtained support for a clade they suggest the name Hexanauplia: Thecostraca + Copepoda. Relations within Allotriocarida remain uncertain: sister taxon to Hexapoda is either Remipedia, or the clade Branchiopoda + Cephalocarida, however, authors are inclined to the first version (see "Conclusion", 4), which is also consistent with von Reumont et al. (2012) results. New proposed by Oakley et al. clades are:
Day of Defeat is a class-based multiplayer first-person shooter video game set in the European theatre of World War II on the Western front. Originally a modification of the 1998 game Half-Life, the rights of the modification were purchased by Valve and released as a full retail title in 2003. Set in the midst of World War II, Day of Defeat includes no single-player campaign, with focus left only on the game's multiplayer aspects. The game favors teamwork and features objective-based gameplay in combination with its system of classes. Maps are primarily made up of narrow paths, all of which typically lead to a few key locations. An official remake of the game, Day of Defeat: Source, was released by Valve in 2005.
Sources: en.wikipedia.org
Native GLP-1 is a short-lived peptide cleared within one to two minutes by dipeptidyl peptidase-4 and related enzymes. Semaglutide keeps the receptor-binding backbone but adds substitutions and a lipid chain. These changes block the main cleavage site and allow reversible albumin binding, extending the half-life to roughly 165 hours.
Albumin is the most abundant protein in plasma and carries molecules that bear fatty-acid chains. Binding shields the peptide from renal filtration and from peptidases, keeping a circulating reservoir. Slow release from this reservoir produces sustained receptor occupancy and supports infrequent dosing.
The insulinotropic effect is glucose-dependent, meaning secretion increases mainly when glucose is elevated. This property is often described as lowering the chance of hypoglycaemia when the compound is used alone. Other glucose-lowering agents used at the same time can still cause low blood glucose.
It is a synthetic peptide of 31 amino acids, built to resemble the natural incretin hormone GLP-1. Because of its size and composition it is handled analytically like other therapeutic peptides, using chromatographic and mass spectrometric methods rather than the techniques typical of small organic drugs.