If you have been reading about GLP-1 receptor agonist and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2025-10-20. Where a claim depends on a specific study, the study is described rather than over-claimed.
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。
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 |
|---|---|---|
| 分子式 | C187H291N45O59 | 按主链与 C18 二酸侧链计算 |
| 分子量 | 约 4113.6 道尔顿 | 游离碱形式，随反离子略有差异 |
| 外观 | 白色至类白色冻干粉末 | 具吸湿性，需干燥保存 |
| 溶解性 | 微溶于水，易溶于碱性缓冲液 | 溶解性随 pH 升高而改善 |
| 等电点 | 约 5.4 | 影响缓冲液选择与聚集倾向 |
Receptor binding triggers G protein signaling that raises intracellular cyclic AMP in pancreatic beta cells. Insulin release follows in a glucose-dependent manner, so secretion increases when blood glucose is elevated and diminishes when it is not. The same signaling suppresses glucagon release from alpha cells and slows gastric emptying, which blunts the post-meal glucose rise. In the brain, receptor activation in regions such as the arcuate nucleus is associated with reduced appetite and lower energy intake. How much each of these effects contributes to overall weight change is not fully settled.
Two structural features account for the prolonged half-life of semaglutide. A modified amino acid at position 8 resists cleavage by dipeptidyl peptidase-4, the enzyme that rapidly degrades native GLP-1. A fatty diacid side chain binds serum albumin, which limits renal clearance and protects the peptide from enzymatic breakdown. These modifications yield a plasma half-life of approximately one week in humans, allowing once-weekly administration. The relationship between plasma concentration and clinical effect varies between individuals, and sources of that variability are still being characterized.
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.
Semaglutide dissolves readily in water and in aqueous buffers near neutral pH. Solubility decreases near the isoelectric point, where net charge is minimal. Common laboratory solvents include phosphate-buffered saline and dilute ammonium bicarbonate. Strongly acidic or basic conditions may accelerate hydrolysis. Working concentrations are usually prepared by diluting a concentrated stock. Vial surfaces can adsorb small amounts of peptide at low concentrations, so carrier proteins or low-binding tubes are sometimes used.
Large randomised trials in adults with type 2 diabetes and in adults with obesity have reported reductions in body weight and improvements in several cardiovascular risk markers. One outcome trial found a lower incidence of major adverse cardiovascular events in participants with diabetes and established cardiovascular disease. Gastrointestinal effects such as nausea and vomiting are the most frequently reported adverse events and often diminish over time. Changes in lean body mass during weight loss are an area of ongoing investigation. Effects in adolescents and in pregnancy are less well characterised, and current labelling advises against use during pregnancy.
Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released after nutrient intake. The molecule contains 31 amino acid residues and differs from the native sequence at several positions. A non-natural residue at position eight resists the enzyme that normally truncates the hormone, while a lysine-linked fatty diacid side chain promotes binding to serum albumin. These two modifications extend the circulating half-life from minutes to roughly one week. The peptide is produced by solid-phase synthesis followed by selective acylation, and its identity and purity are confirmed by spectrometric and chromatographic techniques.
protein sorting Also protein targeting. The set of biological mechanisms by which proteins are directed and transported to appropriate destinations within or outside of the cell. Proteins must often be routed into the interior of organelles, embedded within a membrane, or secreted into the extracellular environment in order to serve their functions, and information contained in the protein itself instructs this delivery process. In eukaryotic cells, an expansive network of organelles and pathways is specialized to facilitate protein sorting, including the endoplasmic reticulum and the Golgi apparatus.
=== Thiol affinity chromatography === Thiols are also known as mercaptans due to their propensity for mercury capture. Thiolates (R-S−) and thioketones (R2C=S), being soft nucleophiles, form strong coordination complexes with mercury(II), a soft electrophile. This mode of action makes them useful for affinity chromatography to separate thiol-containing compounds from complex mixtures. For example, organomercurial agarose gel or gel beads are used to isolate thiolated compounds (such as thiouridine) in a biological sample.
== Comparison with other theories of life == The hypercycle is just one of several current theories of life, including the chemoton of Tibor Gánti, the (M,R) systems of Robert Rosen, autopoiesis (or self-building) of Humberto Maturana and Francisco Varela, and the autocatalytic sets of Stuart Kauffman, similar to an earlier proposal by Freeman Dyson. All of these (including the hypercycle) found their original inspiration in Erwin Schrödinger's book What is Life? but at first they appear to have little in common with one another, largely because the authors did not communicate with one another, and none of them made any reference in their principal publications to any of the other theories. Nonetheless, there are more similarities than may be obvious at first sight, for example between Gánti and Rosen. Until recently there have been almost no attempts to compare the different theories and discuss them together.
Sources: en.wikipedia.org
American cockroaches have three developmental stages: egg, nymph, and adult. Females produce an egg case (ootheca) which protrudes from the tip of the abdomen. On average, females produce 9–10 oothecae, although they can sometimes produce as many as 90. After about two days, the egg cases are placed on a surface in a safe location. Egg cases are about 0.9 cm (0.35 in) long, brown, and purse-shaped. Immature cockroaches emerge from egg cases in 6–8 weeks and require 6–12 months to mature. After hatching, the nymphs feed and undergo a series of 13 moultings (or ecdysis). Adult cockroaches can live up to an additional year, during which females produce an average of 150 young. The American cockroach reproductive cycle can last up to 600 days.
=== Coronary artery disease === Homocysteine, a sulfur based amino acid is the main product of methionine demethylation. Elevated homocysteine is an independent risk factor for cardiovascular disease and inversely correlated to consumed vitamin B12/B6 and folate levels. Homocysteine methylation to methionine is catalyzed by MTR, resulting in appropriate intracellular levels of methionine and tetrahydrofolate, alongside non-toxic homocysteine levels. The GG phenotype promotes the development of premature coronary artery disease (CAD) independent of hyperhomocysteinemia. Hyperhomocysteinemia is associated with cerebral, coronary and peripheral atherosclerotic pathology as it promotes endothelial cell dysfunction, platelet adhesion and vascular smooth muscle cell proliferation. DNA damage and homocysteine levels are proportional to CAD severity. Micronucleus frequency in human lymphocytes, dependent on homocysteine levels increases reactive oxygen species and uracil incorporation in DNA methylation, promoting genetic alterations and point mutations. The (MTRR):c.66A>G, polymorphism containing chromosome is prone to fragmentation. This chromosomal loss or global DNA hypomethylation results in under condensation of pericentromeric heterochromatin, micronucleus formation and elevated risks of aneuploidy. Co-expression of this mutation and the 677T polymorphism in methionine tetrahydrofolate reductase (MTHFR) Methylenetetrahydrofolate reductase act to further the extent of DNA damage.
On 31 August 1980, representatives of workers at the Gdańsk Shipyard, led by an electrician and activist Lech Wałęsa, signed the Gdańsk Agreement with the government that ended their strike. Similar agreements were concluded in Szczecin (the Szczecin Agreement) and in Silesia. The key provision of these agreements was the guarantee of the workers' right to form independent trade unions and the right to strike. Following the successful resolution of the largest labor confrontation in communist Poland's history, nationwide union organizing movements swept the country. Edward Gierek was blamed by the Soviets for not following their "fraternal" advice, not shoring up the communist party and the official trade unions and allowing "anti-socialist" forces to emerge. On 5 September 1980, Gierek was replaced by Stanisław Kania as first secretary of the PZPR. Delegates of the emergent worker committees from all over Poland gathered in Gdańsk on 17 September and decided to form a single national union organization named "Solidarity". While party–controlled courts took up the contentious issues of Solidarity's legal registration as a trade union (finalized by November 10), planning had already begun for the imposition of martial law. A parallel farmers' union was organized and strongly opposed by the regime, but Rural Solidarity was eventually registered (12 May 1981). In the meantime, a rapid deterioration of the authority of the communist party, disintegration of state power and escalation of demands and threats by the various Solidarity–affiliated groups were occurring.
=== 1997–present: CKE, Imasco, Plamondon Companies === In 1997, CKE Restaurants acquired Hardee's from Imasco, but Imasco retained the Roy Rogers trademark and franchise system. The Riese family, which owned 18 Roy Rogers restaurants, sued CKE Restaurants and Imasco for $10 million in 1997, claiming the Roy Rogers chain has been destroyed through "a series of marketing errors of epic proportions." Imasco sold Roy Rogers to Plamondon Enterprises (now Plamondon Companies) in 2002, after three years of negotiation. Roy Rogers was relaunched as Roy Rogers Franchise Company, LLC. Plamondon had already opened the first new Roy Rogers restaurant in Frederick, Maryland, in 2000. At the time of the sale, there were 63 existing Roy Rogers franchises in nine states. In 2021, Roy Rogers announced a strategy to build concentrically out of core markets in the Mid-Atlantic, like Maryland, Virginia, West Virginia, and Pennsylvania. The growth circle would slowly get bigger and include New York, the Eastern Seaboard, and states like Ohio, Tennessee, Florida, Texas, Louisiana, Mississippi, Alabama, and Georgia. The next year, the company announced a new partnership with One Holland Corporation restaurant group and planned to open 10 new Roy Rogers locations over the next six years in the Cincinnati metropolitan area. The new locations would be in Hamilton, Butler, and Clermont counties in Southwest Ohio; Boone, Kenton, and Campbell counties in Northern Kentucky; and Dearborn County in Southeast Indiana. Despite these plans, a spokesperson for One Holland Corp.
Sources: en.wikipedia.org
差别集中在三处：第 8 位残基被非天然氨基酸取代，第 34 位换成精氨酸，第 26 位增加一条脂肪酸侧链。前两处改动降低酶解速率，侧链则通过白蛋白结合延长循环时间。综合结果是半衰期从约两分钟延长到约一周。
胰岛素释放需要细胞内环腺苷酸与钙信号升高，同时依赖葡萄糖代谢产生的协同信号。血糖水平较低时协同信号不足，分泌增强有限。这一机制在降糖效果与低血糖风险之间提供了缓冲。
白蛋白结合是主要原因，它减少肾小球滤过并保护分子免受蛋白酶降解。序列修饰带来的酶解抵抗同样不可忽略，二者共同作用。脂肪链的疏水性还会影响组织分布，但其对总半衰期的贡献程度仍在研究之中。
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.