The short version of 长效肽设计 fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-12-02 and is reviewed periodically as new material appears.
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.
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.
| 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 |
该分子作为 GLP-1 受体的选择性激动剂发挥作用，受体属于 B 类 G 蛋白偶联受体家族，激活后经 Gs 通路提升细胞内环腺苷酸水平。在胰腺 β 细胞，信号促进葡萄糖依赖性的胰岛素释放，血糖偏低时该作用明显减弱。在胰岛 α 细胞，胰高血糖素分泌受到抑制。中枢神经系统与胃肠道同样存在受体表达，相应信号参与食欲调节以及胃排空速率的降低。
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。
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.
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.
The distinction between established facts and open questions matters here. That the peptide binds the GLP-1 receptor and stimulates insulin release in a glucose-dependent manner is well documented. How individual variability in receptor density, gastric emptying rate, and gut microbiome composition shapes response remains an active research area. Long-term outcomes beyond five years of continuous use are not yet fully characterized in published trials, and several extension studies are ongoing.
Late-stage functionalization (LSF) is a desired, chemical or biochemical, chemoselective transformation on a complex molecule to provide at least one analog in sufficient quantity and purity for a given purpose without needing the addition of a functional group that exclusively serves to enable said transformation. Molecular complexity is an intrinsic property of each molecule and frequently determines the synthetic effort to make it. LSF can significantly diminish this synthetic effort, and thus enables access to molecules, which would otherwise not be available or too difficult to access. The requirements for LSF can be met by both C–H functionalization reactions and functional group manipulations. LSF reactions are particularly relevant and often used in the fields of drug discovery and materials chemistry, although no LSF has been implemented in a commercial process.
Ferdinand's actions constituted a definitive de facto break both with the autonomous governments, which had not yet declared formal independence, and with the effort of Spanish liberals to create a representative government that would fully include the overseas possessions. Such a government was seen as an alternative to independence by many in New Spain, Central America, the Caribbean, Quito, Peru, Upper Peru and Chile. Yet the news of the restoration of the "Ancien Régime" did not initiate a new wave of juntas, as had happened in 1809 and 1810, with the notable exception of the establishment of a junta in Cuzco demanding the implementation of the Spanish Constitution. Instead most Spanish Americans were moderates who decided to wait and see what would come out of the restoration of normalcy. In fact, in areas of New Spain, Central America and Quito, governors found it expedient to leave the elected constitutional ayuntamientos in place for several years to prevent conflict with the local society. Liberals on both sides of the Atlantic, nevertheless, continued to conspire to bring back a constitutional monarchy, ultimately succeeding in 1820. The most dramatic example of transatlantic collaboration is perhaps Francisco Javier Mina's expedition to Texas and northern Mexico in 1816 and 1817. Spanish Americans in royalist areas who were committed to independence had already joined the guerrilla movements. However, Ferdinand's actions did set areas outside of the control of the crown on the path to full independence.
The Oddo–Harkins rule holds that elements with even atomic numbers are more common than those with odd atomic numbers, with the exception of hydrogen and beryllium. This rule argues that elements with odd atomic numbers have one unpaired proton and are more likely to capture another, thus increasing their atomic number. In elements with even atomic numbers, protons are paired, with each member of the pair offsetting the spin of the other, enhancing stability. All the alkali metals have odd atomic numbers and they are not as common as the elements with even atomic numbers adjacent to them (the noble gases and the alkaline earth metals) in the Solar System. The heavier alkali metals are also less abundant than the lighter ones as the alkali metals from rubidium onward can only be synthesised in supernovae and not in stellar nucleosynthesis. Lithium is also much less abundant than sodium and potassium as it is poorly synthesised in both Big Bang nucleosynthesis and in stars: the Big Bang could only produce trace quantities of lithium, beryllium and boron due to the absence of a stable nucleus with 5 or 8 nucleons, and stellar nucleosynthesis could only pass this bottleneck by the triple-alpha process, fusing three helium nuclei to form carbon, and skipping over those three elements.
Tiegs was elected in 1944 as a Fellow of the Royal Society, aged 47. In 1954 Oscar Tiegs was one of 23 Foundation Fellows of the Australian Academy of Science, and along with the other 22 foundation fellows was a petitioner to Queen Elizabeth II for the Academy's charter. He, Sydney Sunderland, and Thomas MacFarland Cherry, two other petitioners and foundation members were responsible for drafting the by-laws of the newly formed Academy. The Melbourne University's zoological museum, now called the Tiegs Museum, owes much of the quality of its collection to Oscar Tiegs. He spent time and care improving and extending its holdings, based on his belief in the traditional morphological approach to zoology. Oscar Tiegs was a prodigious worker, and, for example, would take on extra lecturing duties during staff absences to not load his other staff, and only in later years did he balance his time more out of work. He was fond of music, in particular Beethoven and Mozart, and critically appreciated pictures. These interests, of music, art, and literature he shared with his wife Ethel. Some felt Oscar Tiegs, while honest, was direct to the point of bluntness, and had a keen sense of humour. He was known for supportive letters sent to friends during World War II, and the gift parcels sent by him and his wife. Oscar Tiegs' geographical isolation, and his own diffidence probably prevented him from maximising his contribution to zoology, although rather than diffidence others describe it as an unassuming disposition.
== External links == "Mixed Connective Tissue Disease: Causes, Symptoms & Treatment". Cleveland Clinic. 2016-05-26. Nevares, Alana M. (2022-10-06). "Mixed Connective Tissue Disease (MCTD)". Merck Manual Consumer Version.
Sources: en.wikipedia.org
Conventions, festivals and large events were permitted, and all businesses, schools, and places of recreation could be fully open. On July 15, 2020, Pritzker announced a new COVID-19 mitigation plan in the event of a resurgence of COVID-19. The metrics that would be used to determine whether COVID-19's spread in a region required additional mitigations were a sustained increase in 7-day rolling average (7 out of 10 days) in the positivity rate; and one of the following: a sustained 7-day increase in hospital admissions for a COVID-19 or the reduction in hospital capacity. Another metric was three consecutive days averaging greater than or equal to 8% positivity rate.
Since 2009, Durham County Council has provided both county-level and district-level services. Much of the county is also covered by civil parishes, which form a lower tier of local government for their areas.
The National Administrative Department of Statistics (DANE) does not collect religious statistics, and accurate reports are difficult to obtain. However, based on various studies and a survey, about 90% of the population adheres to Christianity, the majority of which (70.9%–79%) are Roman Catholic, while a significant minority (16.7%) adhere to Protestantism (primarily Evangelicalism). Some 4.7% of the population is atheist or agnostic, while 3.5% claim to believe in God but do not follow a specific religion. 1.8% of Colombians adhere to Jehovah's Witnesses and Adventism and less than 1% adhere to other religions, such as the Baháʼí Faith, Islam, Judaism, Buddhism, Mormonism, Hinduism, Indigenous religions, Hare Krishna movement, Rastafari movement, Eastern Orthodoxy, and spiritual studies. The remaining people either did not respond or replied that they did not know. In addition to the above statistics, 35.9% of Colombians reported that they did not practice their faith actively. 1,519,562 people in Colombia, or around 3% of the population reported following an Indigenous religion. While Colombia remains a mostly Roman Catholic country by baptism numbers, the 1991 Colombian constitution guarantees freedom of religion and all religious faiths and churches are equally free before the law.
L-homoserine to form H2O, NH3 and 2-oxobutanoate L-cystine, producing cysteine hydropersulfide, pyruvate and NH3 L-cysteine producing pyruvate, NH3 and H2S In some bacteria and mammals, including humans, this enzyme takes part in generating hydrogen sulfide. Hydrogen sulfide is one of a few gases that was recently discovered to have a role in cell signaling in the body.
Nevertheless, the resistance of extracellular matrix proteins to proteolysis renders their advanced glycation end products less conducive to being eliminated. While the AGE free adducts are released directly into the urine, AGE peptides are endocytosed by the epithelial cells of the proximal tubule and then degraded by the endolysosomal system to produce AGE amino acids. It is thought that these acids are then returned to the kidney's inside space, or lumen, for excretion. AGE free adducts are the major form through which AGEs are excreted in urine, with AGE-peptides occurring to a lesser extent but accumulating in the plasma of patients with chronic kidney failure. Larger, extracellularly derived AGE proteins cannot pass through the basement membrane of the renal corpuscle and must first be degraded into AGE peptides and AGE free adducts. Peripheral macrophage as well as liver sinusoidal endothelial cells and Kupffer cells have been implicated in this process, although the real-life involvement of the liver has been disputed.
Sources: en.wikipedia.org
April III was defensive quality control coach for the Philadelphia Eagles from 2011 to 2012. In 2013, April III moved to the New York Jets as defensive quality control coach and assistant linebacker coach. In 2014, he was promoted to linebackers coach with the Jets. In 2015, April III moved with Rex Ryan from the Jets to the Buffalo Bills and continued to serve as linebackers coach through 2016. On February 1, 2026, April III returned to the Buffalo Bills as the team's new outside linebackers coach, under head coach Joe Brady. April III had accepted a position to be the defensive ends coach with Minnesota in the college ranks only a month earlier. April earned his bachelor's degree in sports management from Louisiana-Lafayette. He is the son of Bobby April Jr., a former NFL and college special teams coordinator. Buffalo Bills profile Wisconsin profile
Encapsulins were discovered in 1994 as a new class of prokaryotic compartments. Prokaryotic cells usually lack membrane compartments typical for eukaryotes. They instead have numerous protein compartments that are capable of accumulating a large number of molecules. The encapsulin systems were first identified through the use of bioinformatics that linked capsid-like proteins to specific operons in bacterial and archaeal genomes. When protein nanocompartments were discovered in 1994, and later renamed encapsulins, they were found in the supernatant fluid of the Brevibacterium linens culture. This bacterium is present on human skin. Since 1994, over 6,000 systems have been identified across 31 bacterial and four archaeal phyla. Encapsulins have also been discovered to be found in extremophiles inhabiting hydrothermal vents. In 2008, encapsulins were identified as protein-based systems for compartmentalization, serving specific functions within cellular organisms. 2008 is also when they started to be called encapsulins. Recent advances in metagenomics, cryo-electron microscopy, and X-ray crystallography have expanded the known diversity and revealed more intricate details about the assembly and functionality of encapsulins.
Tellurium-128 and -130 are essentially stable. They only decay by double beta decay, with half-lives >1020 years. They constitute the major fraction of natural occurring tellurium at 32 and 34% respectively. Tellurium-132 and its daughter 132I are important in the first few days after a criticality. It was responsible for a large fraction of the dose inflicted on workers at Chernobyl in the first week. The isobar forming 132Te/132I is: Tin-132 (half-life 40 s) decaying to antimony-132 (half-life 2.8 minutes) decaying to tellurium-132 (half-life 3.2 days) decaying to iodine-132 (half-life 2.3 hours) which decays to stable xenon-132. The creation of tellurium-126 is delayed by the long half-life (230 k years) of tin-126.
At least several thousand years ago, some humans developed a mutation in the MCM6 gene that keeps the LCT gene turned on even after breast feeding is stopped. Populations that are lactose intolerant lack this mutation. The LCT and MCM6 genes are both located on the long arm (q) of chromosome 2 in region 21. The locus can be expressed as 2q21. The lactase deficiency also could be linked to certain heritages and varies widely. A 2016 study of over 60,000 participants from 89 countries found regional prevalence of lactose malabsorption was "64% (54–74) in Asia (except Middle East), 47% (33–61) in eastern Europe, Russia, and former Soviet Republics, 38% (CI 18–57) in Latin America, 70% (57–83) in the Middle East, 66% (45–88) in northern Africa, 42% (13–71) in northern America, 45% (19–71) in Oceania, 63% (54–72) in sub-Saharan Africa, and 28% (19–37) in northern, southern and western Europe." According to Johns Hopkins Medicine, in the United States lactose intolerance is more common in Asian Americans, African Americans, Mexican Americans, and Native Americans. Analysis of the DNA of 94 ancient skeletons in Europe and Russia concluded that the mutation for lactose tolerance appeared about 4,300 years ago and spread throughout the European population. Some human populations have developed lactase persistence, in which lactase production continues into adulthood probably as a response to the benefits of being able to digest milk from farm animals.
Most engineering materials show some nonlinear elastic and inelastic behavior under operating conditions that involve large loads. In such materials the assumptions of linear elastic fracture mechanics may not hold, that is,
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.