acylated peptide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2025-11-16. Where a claim depends on a specific study, the study is described rather than over-claimed.
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。
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.
The primary target is the GLP-1 receptor, a class B G protein-coupled receptor expressed on pancreatic beta cells, in the gut, and in several brain regions. Receptor activation raises intracellular cyclic AMP, which potentiates glucose-dependent insulin secretion and lowers glucagon release when blood glucose is elevated. Signalling in the hypothalamus and brainstem is associated with reduced appetite and slower gastric emptying. Because the insulinotropic effect depends on prevailing glucose levels, the hypoglycaemic risk of the peptide alone is described as low in most study settings. The relative contribution of peripheral and central actions remains an active research question.
| 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 |
Clinical development of this compound followed earlier short-acting GLP-1 analogues that required frequent injection. Once-weekly subcutaneous formulations entered use after 2017, and an oral formulation using a permeation enhancer later became available. The oral version pairs the peptide with sodium N-(8-[2-hydroxybenzoyl] amino) caprylate, a carrier that improves uptake across the gastric epithelium. Interest has expanded from glycaemic control into weight management and metabolic liver disease. Regulatory status and approved indications differ between countries, and the product remains subject to ongoing safety monitoring.
Semaglutide is a synthetic peptide that acts as an agonist at the glucagon-like peptide-1 receptor. It is a structural analogue of human GLP-1(7-37), modified to resist enzymatic degradation by dipeptidyl peptidase-4. The peptide backbone contains alpha-aminoisobutyric acid at position 8, a substitution that stabilises the helix and slows cleavage. A fatty diacid side chain attached through a linker at lysine 34 promotes binding to serum albumin, which extends the circulating half-life. These two modifications together allow less frequent administration than native GLP-1 requires.
Activation of the GLP-1 receptor couples to Gs signalling and raises intracellular cyclic AMP in pancreatic beta cells. The resulting insulin release depends on prevailing glucose concentrations, so the effect is greater when glucose is elevated. Receptor engagement also suppresses glucagon secretion and slows gastric emptying, which flattens post-meal glucose excursions. In the central nervous system, signalling in hypothalamic and brainstem regions is associated with reduced appetite and lower energy intake. Studies continue to examine effects on cardiac, renal and hepatic endpoints; whether those benefits are independent of weight change remains an open question.
The sequence incorporates alpha-aminoisobutyric acid at position 8, replacing the alanine found in the natural hormone. This substitution blocks the primary DPP-4 recognition site and contributes most of the enzymatic stability. Albumin binding further protects the peptide and reduces the frequency of administration required to maintain active plasma levels. Because the fatty acid chain increases lipophilicity, the compound is formulated as a solution rather than a simple aqueous buffer. Researchers describe the design as an incremental optimization of earlier GLP-1 analogs rather than a wholly new scaffold.
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.
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.
=== Plants === Plants also have receptors that can cause a response to chitin, namely chitin elicitor receptor kinase 1 and chitin elicitor-binding protein. The first chitin receptor was cloned in 2006. When the receptors are activated by chitin, genes related to plant defense are expressed, and jasmonate hormones are activated, which in turn activate systemic defenses. Commensal fungi have ways to interact with the host immune response that, as of 2016, were not well understood. Some pathogens produce chitin-binding proteins that mask the chitin they shed from these receptors.
The matter is automatically referred to the Independent Office for Police Conduct. 24 November – West Midlands Police is placed into special measures by Home Secretary James Cleverly after a review found it was not be effectively investigating or managing the risk to the public of sex offenders. 28 November – The Department for Education launches a consultation on how best to provide a minimum service level in schools in England during teaching strikes. 29 November – Natural England announces that England will be getting a new National Park. The Chilterns, The Cotswolds and Dorset could become new National Parks. Nottingham City Council declares itself effectively bankrupt, with a £23m overspend forecast for the 2023–24 financial year. Bigamist Jason Hayter of Frinton-on-Sea, Essex, is sentenced to eight weeks in prison suspended for 12 months and placed under night curfew for being married to two women simultaneously. 30 November – At least three police officers are injured during disorder ahead of a football match between Aston Villa and Legia Warsaw in Birmingham. Aston Villa confirms that no away fans were let into the stadium on the advice of police following the trouble.
1848: American astronomer Maria Mitchell became the first woman elected to the American Academy of Arts and Sciences; she had discovered a new comet the year before. 1848–1849: English scientist Mary Anne Whitby, a pioneer in western silkworm cultivation, collaborated with Charles Darwin in researching the hereditary qualities of silkworms. 1850: The American Association for the Advancement of Sciences accepted its first women members: astronomer Maria Mitchell, entomologist Margaretta Morris, and science educator Almira Hart Lincoln Phelps.
=== Cot–Cz === Frank Albert Cotton (1930–2007), American chemist known for research on transition metals and as coauthor of Advanced Inorganic Chemistry, 2000 Wolf Prize in Chemistry Charles Coulson (1910–1974), British theoretical chemist, pioneer of the application of quantum theory to problems of molecular structure Archibald Scott Couper (1831–1892), British chemist who developed the concept of tetravalent carbon atoms linking together to form large molecules James Crafts (1839–1917), American chemist, developer of Friedel–Crafts reaction for alkylation and acylation Donald J. Cram (1919–2001), American chemist, winner of the 1987 Nobel Prize in Chemistry for development of molecules with structure-specific interactions of high selectivity William Crookes (1832–1919), British chemist who discovered thallium, and was a pioneer of vacuum tubes Alexander Crum Brown (1838–1922), Scottish organic chemist who developed the concept of tetravalent carbon atoms linking together to form large molecules Paul J.
== Comparative anatomy == Ligaments are similar to tendons and fasciae as they are all made of connective tissue. The differences among them are in the connections that they make: ligaments connect one bone to another bone, tendons connect muscle to bone, and fasciae connect muscles to other muscles. These are all found in the skeletal system of the human body. Ligaments cannot usually be regenerated naturally; however, there are periodontal ligament stem cells located near the periodontal ligament which are involved in the adult regeneration of periodontist ligament. The study of ligaments is known as desmology.
Sources: en.wikipedia.org
=== Acute kidney impairment === Acute kidney impairment is one of the more complicated complications of Rhabdomyolysis. The risk of kidney injuries is increased from factors such as hypovolemia, abnormalities from electrolytes, and the severity of muscle injury. Kidney dysfunction typically develops 1–2 days after the initial muscle damage. If supportive treatment is inadequate to manage this, renal replacement therapy (RRT) may be required. RRT removes excess potassium, acid, and phosphate that accumulate when the kidneys are unable to function normally and is required until kidney function is regained. Three main modalities of RRT are available: hemodialysis, continuous hemofiltration and peritoneal dialysis. The former two require access to the bloodstream (a dialysis catheter), and peritoneal dialysis is achieved by instilling fluid into the abdominal cavity and later draining it. Hemodialysis, which is normally done several times a week in chronic kidney disease, is often required daily in rhabdomyolysis. Its advantage over continuous hemofiltration is that one machine can be used multiple times a day, and that continuous administration of anticoagulant drugs is not necessary. Hemofiltration is more effective at removing large molecules from the bloodstream, such as myoglobin, but this does not seem to confer any particular benefit. Peritoneal dialysis may be difficult to administer in someone with severe abdominal injury, and it may be less effective than the other modalities.
We feel that the Arabs and Jews are cousins in race, suffering similar oppression at the hands of powers stronger than themselves, and by a happy coincidence have been able to take the first step toward the attainment of their national ideals together. We Arabs, especially the educated among us, look with deepest sympathy on the Zionist movement ... We will do our best, in so far as we are concerned, to help them through; we will wish the Jews a most hearty welcome home.When the letter was tabled at the Shaw Commission in 1929, Rustam Haidar spoke to Faisal in Baghdad and cabled that Faisal had "no recollection that he wrote anything of the sort". In January 1930, Haidar wrote to a newspaper in Baghdad that Faisal: "finds it exceedingly strange that such a matter is attributed to him as he at no time would consider allowing any foreign nation to share in an Arab country". Awni Abd al-Hadi, Faisal's secretary, wrote in his memoirs that he was not aware that a meeting between Frankfurter and Faisal took place and that: "I believe that this letter, assuming that it is authentic, was written by Lawrence, and that Lawrence signed it in English on behalf of Faisal. I believe this letter is part of the false claims made by Chaim Weizmann and Lawrence to lead astray public opinion." According to Allawi, the most likely explanation for the Frankfurter letter is that a meeting took place, a letter was drafted in English by Lawrence, but that its "contents were not entirely made clear to Faisal.
==== In alchemy ==== Sulfur has also been a major ingredient in alchemy since its early days, different branches of Indian, Muslim and European alchemists ascribing it esoteric symbolism based on its strong bond with mercury and the interactions between the two elements. Greco-Alexandrian practitioners of Hellenistic alchemy like Mary the Jewess and Zosimos of Panopolis were interested in sulfur and sulfur compounds, and mentioned them in their writings. Indian alchemists, practitioners of the "science of chemicals" (Sanskrit: रसशास्त्र, romanized: rasaśāstra), wrote extensively about the use of sulfur in alchemical operations with mercury, from the eighth century AD onwards. In the rasaśāstra tradition, sulfur is called "the smelly" (गन्धक, gandhaka), and is thought to represent the feminine principle, the menstrual blood of the goddess Gauri (Shakti), while mercury is its male counterpart, the semen of Shiva. Alchemists in Europe and the Islamic world (basing themselves off the "sulfur-mercury theory of metals" from Arabic alchemical texts of the ninth century) had the opposite imagery in their traditions, with sulfur representing the masculine principle and mercury the feminine one, mixing together to form various metals. This theory of metals was very influential during the Middle Ages, and persisted until the eighteenth century, when Lavoisier proved that metals were distinct elements. In the sixteenth century, Paracelsus added Salt as a third element to the Sulfur-Mercury dyad, making them the three basic pillars of alchemy according to his theory: the Tria Prima.
The NSA commenced warrantless surveillance of telecommunications, which was sometimes criticized as permitting the agency "to eavesdrop on telephone and e-mail communications between the United States and people overseas without a warrant." In response to requests by intelligence agencies, the United States Foreign Intelligence Surveillance Court permitted an expansion of powers by the U.S. government in seeking, obtaining, and sharing information on U.S. citizens, as well as non-Americans around the world.
==== Basis for different types of T-cell help ==== How these different methods operate, the forms of antigen expressed, and the different profiles of T-cell help is not understood. It was thought that the relatively large amounts of DNA used in IM injection were responsible for the induction of TH1 responses. However, evidence shows no dose-related differences in TH type. The type of T-cell help raised is determined by the differentiated state of antigen presenting cells. Dendritic cells can differentiate to secrete IL-12 (which supports TH1 cell development) or IL-4 (which supports TH2 responses). pDNA injected by needle is endocytosed into the dendritic cell, which is then stimulated to differentiate for TH1 cytokine (IL-12) production, while the gene gun bombards the DNA directly into the cell, thus bypassing TH1 stimulation.
Sources: en.wikipedia.org
These particles cannot be filtered out before injection, and will accumulate in the body over time, especially in the lungs and eyes, producing various complications such as pulmonary hypertension, an irreversible and progressive disease. The formulation sold under the brand name Methadose (flavored liquid suspension for oral dosing, commonly used for maintenance purposes) should not be injected either. Information leaflets included in packs of UK methadone tablets state that the tablets are for oral use only and that use by any other route can cause serious harm. In addition to this warning, additives have now been included in the tablet formulation to make the use of them by the IV route more difficult. Methadone is also available in ampoules with strength of 50mg/ml & 10mg/ml for IV/IM/SC use in the UK. Prescribing the injectable formulation was more common in the 90s with prescribers reporting that up to 9-10% of all methadone prescription were for ampoules. This practice is much less common nowadays
Severe side effects are rare and occur mostly in those with poor immune function. Its use in people with HIV/AIDS should be done with care. It is not recommended during pregnancy; however, the few times it has been given during pregnancy no problems resulted. The vaccine is available either by itself or along with the MMR vaccine, in a version known as the MMRV vaccine. It is made from weakened virus. A live attenuated varicella vaccine, the Oka strain, was developed by Michiaki Takahashi and his colleagues in Japan in the early 1970s. American vaccinologist Maurice Hilleman's team developed a chickenpox vaccine in the United States in 1981, based on the "Oka strain" of the varicella virus. The chickenpox vaccine first became commercially available in 1984. It was first licensed for use in the US by Merck, under the brand name Varivax, in 1995. It is on the World Health Organization's List of Essential Medicines.
The main application of ZDDPs are as anti-wear additives in lubricants including greases, hydraulic oils, and motor oils. ZDDPs also act as corrosion inhibitors and antioxidants. Concentrations in lubricants range from 600 ppm for modern, energy-conserving low-viscosity oils to 3000 ppm in some racing oils. It has been reported that zinc and phosphorus emissions may damage catalytic converters and standard formulations of lubricating oils for gasoline engines now have reduced amounts of the additive due to the API limiting the concentration of this additive in new API SM and SN oils; however, this affects only 20- and 30-grade "ILSAC" oils. Grades 40 and higher have no regulation regarding the concentration of ZDDP, except for diesel oils meeting the API CJ-4 specification which have had the level of zddp reduced slightly, although most diesel Heavy-Duty Engine oils still have a higher concentration of this additive. Crankcase oils with reduced ZDDP have been cited as causing damage to, or failure of, classic/collector car flat-tappet camshafts and lifters which undergo very high boundary layer pressures and/or shear forces at their contact faces, and in other regions such as main bearings, and piston rings and pins. Roller camshafts/followers are more commonly used to reduce camshaft lobe friction in modern engines.
Algae are used as foods in many countries: China consumes more than 70 species, including fat choy, a cyanobacterium considered a vegetable; Japan, over 20 species such as nori and aonori; Ireland, dulse; Chile, cochayuyo. Laver is used to make laverbread in Wales, where it is known as bara lawr. In Korea, green laver is used to make gim. Some of the most commonly used microalgae as food are:
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。
Native GLP-1 is degraded within minutes by dipeptidyl peptidase-4 and neutral endopeptidases. Semaglutide carries a non-natural amino acid at position eight that blocks that cleavage, and a fatty diacid side chain that binds albumin. The result is a much longer duration of action than the native hormone.