The short version of 二肽基肽酶-4 fits in a sentence. The long version — which is the one that helps — is below.
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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.
Receptor activation follows the canonical Gs pathway: binding increases intracellular cyclic AMP, which promotes protein kinase A activity. In pancreatic beta cells this amplifies glucose-dependent insulin release, so secretion rises when blood glucose is high and changes little when it is low. The same signalling suppresses glucagon release from alpha cells and slows gastric emptying. Receptors in the hypothalamus and brainstem are thought to contribute to reduced appetite and lower energy intake. Which of these effects dominates clinical outcomes remains an area of active study.
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.
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.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1 (GLP-1), a hormone released from intestinal L-cells after food intake. The compound belongs to the incretin mimetic class and acts at GLP-1 receptors distributed across pancreatic, gastrointestinal, cardiovascular, and central nervous system tissues. Compared with native GLP-1, the molecule carries structural changes that extend its activity from minutes to roughly one week. It is studied for glycemic control in type 2 diabetes and for weight management, and its effects on cardiovascular and other outcomes remain active research areas.
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.
| 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 |
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.
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.
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。
German Doner Kebab (GDK) is a fast casual kebab chain, specialising in German doner kebabs, owned by Hero Brands since 2017. Tracing its heritage to a restaurant in Berlin in 1989, the first site opened in Dubai by Farshad Abbaszadeh and his wife Leila Zomorrodian in 2013. The company was purchased with a majority share in 2017 by Hero Brands and moved its headquarters to Glasgow. The company operates more than 160 restaurants throughout the United Kingdom, Sweden, North America and the Middle East.
Systems neuroscience research centers on the structural and functional architecture of the developing human brain, and the functions of large-scale brain networks, or functionally-connected systems within the brain. Alongside brain development, systems neuroscience also focuses on how the structure and function of the brain enables or restricts the processing of sensory information, using learned mental models of the world, to motivate behavior. Questions in systems neuroscience include how neural circuits are formed and used anatomically and physiologically to produce functions such as reflexes, multisensory integration, motor coordination, circadian rhythms, emotional responses, learning, and memory. In other words, this area of research studies how connections are made and morphed in the brain, and the effect it has on human sensation, movement, attention, inhibitory control, decision-making, reasoning, memory formation, reward, and emotion regulation. Specific areas of interest for the field include observations of how the structure of neural circuits effect skill acquisition, how specialized regions of the brain develop and change (neuroplasticity), and the development of brain atlases, or wiring diagrams of individual developing brains. The related fields of neuroethology and neuropsychology address the question of how neural substrates underlie specific animal and human behaviors. Neuroendocrinology and psychoneuroimmunology examine interactions between the nervous system and the endocrine and immune systems, respectively.
Excesses of stable 129Xe in meteorites have been shown to result from decay of "primordial" iodine-129 produced newly by the supernovas that created the dust and gas from which the Solar System formed. This isotope has long decayed and is thus referred to as "extinct". Historically, 129I was the first extinct radionuclide to be identified as present in the early Solar System. Its decay is the basis of the I-Xe iodine-xenon radiometric dating scheme, which covers the first 85 million years of Solar System evolution.
=== Long term exposure of residents living near medical supply warehouses === Residents living near Cardinal Health's warehouse, which holds sterilized medical supplies, in El Paso Texas reported respiratory symptoms in 2021. Some sources estimate these large warehouses holding sterilized medical equipment outgas more ethylene oxide than some sterilization plants due to laxer regulations. Further investigation discovered people living near these warehouses are being exposed to ethylene oxide levels sufficient to increase cancer risk to more than 1 in 10,000.
Lewis Namier (27 June 1888 – 19 August 1960), British historian of Polish-Jewish ancestry; descendant of Rabbi Elijah ben Solomon Zalman,(Hebrew: ר' אליהו בן שלמה זלמן) known as the Vilna Gaon; author of over twenty scholarly texts and authoritative monographs on sociopolitical typology and geopolitical analysis; held positions with Propaganda Department (1915–17), the Department of Information (1917–18) and with Political Intelligence Department of Foreign Office (1918–20); following defeat of Germany in World War One, Namier joined British delegation at Versailles Peace Conference of 1919; later Namier, who was a long-time Zionist, worked as political secretary for the Jewish Agency in Palestine (1929–31) and was close friend and associate of Chaim Weizmann; active in Zionist groups, lobbying British government to allow creation of Jewish Fighting Force in Mandate of Palestine and from 1933 was engaged in efforts on behalf of Jewish refugees from Germany. Namier used prosopography or collective biography of every Member of Parliament (MP) and peer who sat in the British Parliament in the latter 18th century to reveal that local interests, not national ones, often determined how parliamentarians voted. As former patient of Sigmund Freud, Namier was a believer in psychohistory. Saul Newman, anarchist scholar and activist,(born 22 March 1972) is a British political theorist who writes on post-anarchism. He is professor of political theory at Goldsmiths College, University of London.
Sources: en.wikipedia.org
Alpha-fetoprotein (AFP) is significantly expressed in foetal liver. However, the mechanism that led to the suppression of AFP synthesis in adults is not fully known. Exposure of the liver to cancer-causing agents and arrest of liver maturation in childhood can lead to the rise in AFP. AFP can reach until 400–500 μg/L in hepatocellular carcinoma. AFP concentration of more than 400 μg/L is associated with greater tumour size, involvement of both lobes of liver, portal vein invasion and a lower median survival rate.
Methylnaltrexone (MNTX, brand name Relistor), used in form of methylnaltrexone bromide (INN, USAN, BAN), is a medication that acts as a peripherally acting μ-opioid receptor antagonist that acts to reverse some of the side effects of opioid drugs such as constipation without significantly affecting pain relief or precipitating withdrawals. Because MNTX is a quaternary ammonium cation, it cannot cross the blood–brain barrier, and so has antagonist effects throughout the body, counteracting effects such as itching and constipation, but without affecting opioid effects in the brain such as pain relief. However, since a significant fraction (up to 60%) of opioid analgesia can be mediated by opioid receptors on peripheral sensory neurons, particularly in inflammatory conditions such as arthritis, traumatic or surgical pain, MNTX may increase pain under such circumstances.
(Indeed, testosterone, DHT, and estradiol levels are actually raised by bicalutamide treatment, and for this reason, levels of 3α- and 3β-androstanediol might be elevated to some degree similarly.) These metabolites of testosterone have been found to have AR-independent positive effects on sexual motivation, and may be involved in the preservation of sexual interest and function by bicalutamide and other NSAAs. However, a study found that a combination of bicalutamide and dutasteride, a 5α-reductase inhibitor and inhibitor of neurosteroid biosynthesis, produced fewer sexual side effects than GnRH analogue therapy, specifically suggesting the role of estradiol in the preservation sexual interest and function with bicalutamide monotherapy rather than of DHT metabolites. As an alternative possibility to testosterone metabolites preserving sexual desire and function with bicalutamide, it has been suggested that bicalutamide may not be able to block the actions of androgens in the brain to a degree sufficient to cause substantial sexual impairment.
Note that in the context of metal-ligand complex formation, the equilibrium constants for the formation of metal complexes are usually defined as association constants. In that case, the equilibrium constants for ligand protonation are also defined as association constants. The numbering of association constants is the reverse of the numbering of dissociation constants; in this example
While earlier centuries also saw significant developments, the 20th century was distinguished by the unprecedented pace and global scale of economic, technological, and cultural changes. Still, advancing technology and medicine have had a great impact even in the Global South. Large-scale industry and more centralized media made brutal dictatorships possible on an unprecedented scale in the middle of the century, leading to wars that were also unprecedented. However, the increased communications contributed to democratization. Technological developments included the development of airplanes and space exploration, nuclear technology, advancement in genetics, and the dawning of the Information Age. Major political developments included the Israeli–Palestinian conflict, two world wars, and the Cold War. It also saw the former British Empire lose most of its remaining political power over Commonwealth countries, most notably by the dividing of the British crown into several sovereignties by the Statute of Westminster, the patriation of constitutions by the Canada Act 1982, and the Australia Act 1986, as well as the independence of countries like India, Pakistan, South Africa, and Ireland.
Sources: en.wikipedia.org
Corey Taylor − vocals, guitar on track 17, additional guitar on tracks 4, 8 and 12 James Root − guitar (on all tracks except 18), drums on track 15 Josh Rand − guitar (on all tracks except 18) Shawn Economaki − bass (on all tracks except 17 and 18) Roy Mayorga − drums (on all tracks except 1, 15, 17 and 18) Additional personnel
===== Chain of any number of decays ===== For the general case of any number of consecutive decays in a decay chain, i.e. A1 → A2 ··· → Ai ··· → AD, where D is the number of decays and i is a dummy index (i = 1, 2, 3, ..., D), each nuclide population can be found in terms of the previous population. In this case N2 = 0, N3 = 0, ..., ND = 0. Using the above result in a recursive form:
The most commonly used synthetic membrane devices (modules) are flat sheets/plates, spiral wounds, and hollow fibers. Flat membranes used in filtration and separation processes can be enhanced with surface patterning, where microscopic structures are introduced to improve performance. These patterns increase surface area, optimize water flow, and reduce fouling, leading to higher permeability and longer membrane lifespan. Research has shown that such modifications can significantly enhance efficiency in water purification, energy applications, and industrial separations. Flat plates are usually constructed as circular thin flat membrane surfaces to be used in dead-end geometry modules. Spiral wounds are constructed from similar flat membranes but in the form of a "pocket" containing two membrane sheets separated by a highly porous support plate. Several such pockets are then wound around a tube to create a tangential flow geometry and to reduce membrane fouling. Hollow fiber modules consist of an assembly of self-supporting fibers with dense skin separation layers, and a more open matrix helping to withstand pressure gradients and maintain structural integrity. The hollow fiber modules can contain up to 10,000 fibers ranging from 200 to 2500 μm in diameter; The main advantage of hollow fiber modules is the very large surface area within an enclosed volume, increasing the efficiency of the separation process.
STEP 2: The 2-methylpropanol-TPP is oxidized to form an acyl group while being simultaneously transferred to the lipoyl cofactor on E2. Note that TPP is regenerated. The proper arrow-pushing mechanism is shown in Figure 4.
=== Elucidation of mechanism of action === Seminal studies that uncovered the mechanism of action for isoniazid were largely performed in M. smegmatis, a model for the slow-growing M. tuberculosis. In 1992, Stewart Cole and colleagues discovered that isoniazid was active in resistant M. smegmatis only when KatG, a catalase-peroxidase, was expressed; KatG is now understood to be critical for the metabolism of the prodrug isoniazid into its active forms.. At the Albert Einstein College of Medicine, William R. Jacobs Jr. and coworkers discovered that inhA—which they also found to encode an NADH-specific enoyl-acyl carrier protein reductase—as isoniazid's primary target The isoniazid-NAD adduct was also shown to bind and inhibit InhA, the protein product of inhA.
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.
Native GLP-1 is degraded within minutes by dipeptidyl peptidase-4 and cleared quickly. Semaglutide carries a position 8 substitution that blocks that cleavage and a fatty diacid chain that binds albumin. Together these changes extend its circulating half-life to about one week.