The short version of Aib substitution fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-12-31. Anything still debated is marked as such rather than presented as settled.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1, a hormone released from intestinal L-cells after food intake. It contains 31 amino acids and differs from native GLP-1 through modifications that slow enzymatic breakdown. The peptide was developed to extend the short circulating half-life of endogenous GLP-1, which is measured in minutes. Researchers introduced the compound in the early 2010s. Two backbone changes and a fatty acid side chain define its structure, distinguishing it from earlier GLP-1 receptor agonists.
The compound binds the GLP-1 receptor on pancreatic beta cells and other tissues, activating a G-protein signaling cascade that raises intracellular cyclic AMP. This action increases glucose-dependent insulin secretion when blood glucose is elevated, while binding also slows gastric emptying and reduces glucagon release. In the central nervous system, receptor activation in the hypothalamus and brainstem contributes to reduced appetite. The fatty acid chain binds albumin, which protects the peptide from renal filtration and enzymatic degradation. This albumin binding is central to its extended circulation time.
Native GLP-1 is degraded rapidly by dipeptidyl peptidase-4. Semaglutide resists this cleavage because alanine at position 8 is replaced by alpha-aminoisobutyric acid. A second substitution at position 34 introduces arginine, which further stabilizes the peptide. The most distinctive modification is a spacer and C18 fatty diacid attached at lysine 26, enabling strong albumin affinity. These three changes together produce a half-life measured in days rather than minutes, and the same structural logic underlies other long-acting analogs in this class.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide | 31 amino acids |
| Backbone modification | Aib at position 8 | Blocks DPP-4 cleavage |
| Fatty acid chain | C18 diacid | Supports albumin binding |
| Native half-life | 1 to 2 minutes | Endogenous GLP-1 |
| Analog half-life | Approximately one week | Extended by albumin binding |
Having in mind the constitutional position of the Bohemian Crown and being conscious of the glory and power which that Crown has given us and our predecessors… we gladly recognise the rights of the kingdom and are prepared to renew that recognition through our coronation oath. For the planned coronation, the composer Bedřich Smetana had written the opera Libuše, but the ceremony did not take place. The creation of the German Empire, domestic opposition from German-speaking liberals (especially German-Bohemians) and from Hungarians doomed the Fundamental Articles. Hohenwart resigned and nothing changed. Many Czech people were waiting for political changes in monarchy, including Tomáš Garrigue Masaryk and others. Masaryk served in the Reichsrat (Upper House) from 1891 to 1893 in the Young Czech Party and again from 1907 to 1914 in the Realist Party (which he had founded in 1900), but he did not campaign for the independence of Czechs and Slovaks from Austria-Hungary. In Vienna in 1909 he helped Hinko Hinković's defense in the fabricated trial against prominent Croats and Serbs members of the Serbo-Croatian Coalition (such as Frano Supilo and Svetozar Pribićević), and others, who were sentenced to more than 150 years and a number of death penalties. The Bohemian question would remain unresolved for the entirety of Franz Joseph's reign.
==== MeSH D12.776.835.700.350 – gtp phosphohydrolase-linked elongation factors ==== MeSH D12.776.835.700.350.200 – peptide elongation factor g MeSH D12.776.835.700.350.700 – peptide elongation factor tu MeSH D12.776.835.700.350.800 – peptide elongation factor 1 MeSH D12.776.835.700.350.850 – peptide elongation factor 2
Fentanyl's most common side effects, which affect more than 10% of people, include nausea, vomiting, constipation, dry mouth, somnolence, confusion, and asthenia (weakness). Less frequently, in 3–10% of people, fentanyl can cause abdominal pain, headache, fatigue, anorexia and weight loss, dizziness, nervousness, anxiety, depression, flu-like symptoms, dyspepsia (indigestion), shortness of breath, hypoventilation, apnea, and urinary retention. Fentanyl use has also been associated with aphasia. Despite being a more potent analgesic, fentanyl tends to induce less nausea, as well as less histamine-mediated itching, than morphine. In rare cases, serotonin syndrome is associated with fentanyl use. Existing studies advise medical practitioners to exercise caution when combining selective serotonin reuptake inhibitor (SSRI) drugs with fentanyl. The duration of action of fentanyl has sometimes been underestimated, leading to harm in a medical context. In 2006, the United States Food and Drug Administration (FDA) began investigating several respiratory deaths, but doctors in the United Kingdom were not warned of the risks with fentanyl until September 2008. The FDA reported in April 2012 that twelve young children had died and twelve more had become seriously ill from separate accidental exposures to fentanyl skin patches.
== History == DART resulted from conversations between Laramee and Cody about the development of an atmospheric pressure ion source to replace the radioactive sources in handheld chemical weapons detectors. DART was developed in late 2002 to early 2003 by Cody and Laramee as a new atmospheric pressure ionization process, and a US patent application was filed in April 2003. Although the development of DART actually predated the desorption electrospray ionization (DESI) ion source, the initial DART publication did not appear until shortly after the DESI publication, and both ion sources were publicly introduced in back-to-back presentations by R. G. Cooks and R. B. Cody at the January 2005 ASMS Sanibel Conference. DESI and DART are considered as pioneer techniques in the field of ambient ionization, since they operate in the open laboratory environment and do not require sample pretreatment. In contrast to the liquid spray used by DESI, the ionizing gas from the DART ion source contains a dry stream containing excited state species.
Sources: en.wikipedia.org
During the mid-19th century, canned food became a status symbol among middle-class households in Europe, being something of a frivolous novelty. Early methods of manufacture employed poisonous lead solder for sealing the cans. Studies in the 1980s attributed the lead from the cans as a factor in the disastrous outcome of the 1845 Franklin expedition to chart and navigate the Northwest Passage. However, studies in 2013 and 2016 suggested that lead poisoning was likely not a factor, and that the crew's ill health may, in fact, have been due to malnutrition—specifically zinc deficiency—possibly due to a lack of meat in their diet. Increasing mechanization of the canning process, coupled with a huge increase in urban populations across Europe, resulted in a rising demand for canned food. A number of inventions and improvements followed, and by the 1860s smaller machine-made steel cans were possible, and the time to cook food in sealed cans had been reduced from around six hours to thirty minutes.
A lotus seed or lotus nut is the seed of plants in the genus Nelumbo, particularly the species Nelumbo nucifera. The seeds are used in Asian cuisine and traditional medicine. Mostly sold in dried, shelled form, the seeds are rich in protein, B vitamins, and dietary minerals.
=== Extracts === Products stating various E. longifolia extract ratios of 1:50, 1:100, and 1:200 are common on the market. However, extracts based on this ratio system are often misleading and hard to verify. Scientific research done on herbal products in general indicates that in many cases the content of bioactive constituents varies between products. Another option is for extraction techniques to use standardization methods to monitor the bioactive content and quality of the extract against standardization markers. Among standardization markers that have been used for E. longifolia are eurycomanone, total protein, total polysaccharide and glycosaponin, which have been recommended in a technical guideline developed by the Scientific and Industrial Research Institute of Malaysia.
== History == The idea of recombinant DNA was first proposed by Peter Lobban, a graduate student of Prof. Dale Kaiser in the Biochemistry Department at Stanford University Medical School. The first publications describing the successful production and intracellular replication of recombinant DNA appeared in 1972 and 1973, from Stanford and UCSF. In 1980 Paul Berg, a professor in the Biochemistry Department at Stanford and an author on one of the first papers was awarded the Nobel Prize in Chemistry for his work on nucleic acids "with particular regard to recombinant DNA". Werner Arber, Hamilton Smith, and Daniel Nathans shared the 1978 Nobel Prize in Physiology or Medicine for the discovery of restriction endonucleases which enhanced the techniques of rDNA technology. Stanford University applied for a U.S. patent on recombinant DNA on November 4, 1974, listing the inventors as Herbert W. Boyer (professor at the University of California, San Francisco) and Stanley N. Cohen (professor at Stanford University); this patent, U.S. 4,237,224A, was awarded on December 2, 1980. The first licensed drug generated using recombinant DNA technology was human insulin, developed by Genentech and licensed by Eli Lilly and Company.
=== Post-hoc analysis and proton inventory === It is necessary to conduct a post-hoc analysis to determine the buffer or solvent-independent enthalpy from the experimental thermodynamics. The collected experimental data reflects not only the binding thermodynamics of the interaction of interest, but any contributing competing equilibria associated to it. A post-hoc analysis can be performed to determine the buffer or solvent-independent enthalpy from the experimental thermodynamics, by simply going through the process of Hess' law. Below example shows a simple interaction between a metal ion (M) and a ligand (L). B represents the buffer used for this interaction and
Sources: en.wikipedia.org
=== Defence and intraspecific combat === A few species are able to use chemical defences against predators; some Procellariiformes can eject an unpleasant stomach oil against an aggressor, and some species of pitohuis from New Guinea have a powerful neurotoxin in their skin and feathers. A lack of field observations limit our knowledge, but intraspecific conflicts are known to sometimes result in injury or death. The screamers (Anhimidae), some jacanas (Jacana, Hydrophasianus), the spur-winged goose (Plectropterus), the torrent duck (Merganetta) and nine species of lapwing (Vanellus) use a sharp spur on the wing as a weapon. The steamer ducks (Tachyeres), geese and swans (Anserinae), the solitaire (Pezophaps), sheathbills (Chionis), some guans (Crax) and stone curlews (Burhinus) use a bony knob on the alular metacarpal to punch and hammer opponents. The jacanas Actophilornis and Irediparra have an expanded, blade-like radius. The extinct Xenicibis was unique in having an elongate forelimb and massive hand which likely functioned in combat or defence as a jointed club or flail. Swans, for instance, may strike with the bony spurs and bite when defending eggs or young.
=== Other lawsuits, investigations, and prosecutions === In August 2019, Schmitt withdrew a legal brief that argued that the First Amendment allowed government officials to withhold records from a freedom of information request, following criticism from transparency advocates who noted that the brief did not cite any case law. A Freedom Center of Missouri representative raised concern that the argument is similar to a case involving Governor Mike Parson, which Schmitt had not yet ruled on. Under Schmitt, the attorney general's office sued the city of Marshfield, Missouri, alleging that it maintained a ticket-quota system, in violation of the state law Schmitt had sponsored as state senator banning such quotas. In 2020, the suit ended in a settlement in which the city agreed to maintain a compliance program and have its state officials undergo training on the law. In September 2019, a bipartisan group of state attorneys general, including Schmitt, launched an antitrust investigation against Google. The attorneys general accused Google of prioritizing searches for companies that advertise on the search engine platform in violation of antitrust law.
== Signs and symptoms == Urethral diverticula are often asymptomatic and symptoms that are present tend to be nonspecific. They can co-occur with cancer, in approximately 6-9% of cases, most commonly adenocarcinoma, but also including squamous cell carcinoma and transitional cell carcinoma. Approximately 10% of cases co-occur with kidney stones. There are 2 types of urethral diverticulums. Congenital and acquired. In infancy usually the urethral diverticulum is congenital but in rare instances acquired urethral diverticulum can be seen in infancy specially following traumatic catheterization. Common symptoms of urethral diverticulum include incontinence, urinary frequency and urgency, pain during sex, and pain during urination. Other symptoms include pain localized to the urethra or pelvis and frequent urinary tract infection. When urethral diverticulum becomes severe, a painful mass can sometimes be felt inside the introitus of the vagina, which can discharge pus. If the mass is hard or bleeds, complications like cancer or kidney stones may be present.
"History of the Laboratory". LLNL. July 14, 2002. Archived from the original on October 12, 2006. Serving the Nation for Fifty Years: 1952–2002 Lawrence Livermore National Laboratory [LLNL], Fifty Years of Accomplishments (PDF) (Report). LLNL. 2002. UCRL-AR-148833. Archived from the original (PDF) on October 15, 2011. Retrieved August 26, 2013. LLNL Industrial Partnerships and Commercialization (IPAC) (official website)
Sources: en.wikipedia.org
It is a synthetic analog of GLP-1 produced through medicinal chemistry to resist enzymatic degradation. The design goal was longer circulation than the native hormone.
A fatty acid side chain attaches the peptide to serum albumin, which shields it from kidney filtration and protease activity. This interaction is the main reason its circulation time is extended.
No. The native hormone is GLP-1, and semaglutide is an engineered variant with three deliberate structural alterations. It does not appear in unmodified biological sources.
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.