This is a working overview of incretin, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-05-30 and is reviewed periodically as new material appears.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized form |
| Solubility | Water and aqueous buffers | Near neutral pH |
| Storage temperature | Minus 20 to minus 80 C | Long-term, lyophilized |
| Analytical method | RP-HPLC | Purity assessment |
| Typical purity | Greater than 95 percent | Research-grade material |
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.
The semaglutide sequence is a 31-residue analogue of human GLP-1, altered at three positions relative to the parent hormone. Aminoisobutyric acid replaces alanine at position 8, arginine replaces lysine at position 34, and a lipophilic diacid is attached to lysine 26 through a short linker. These features are reported consistently in the structural literature. The position 8 substitution blocks recognition by dipeptidyl peptidase-4, while the attached chain drives strong, reversible association with a carrier protein in blood.
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.
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.
The company that developed the compound filed it as a long-acting analogue, and it gained first approval in 2017 for type 2 diabetes. Later authorisations from several regulators extended the indication to chronic weight management, and the World Health Organization added the glucagon-like peptide-1 receptor agonist drug class to its model list of essential medicines in 2023. Production uses solid-phase peptide synthesis followed by side-chain conjugation and chromatographic purification. Supply constraints and cost differences across regions are well documented. Literature on long-term outcomes continues to grow, with many trials reporting surrogate endpoints rather than hard clinical endpoints.
Semaglutide is a synthetic peptide of thirty-one amino acids that shares roughly ninety-four percent sequence identity with human glucagon-like peptide-1. Two substitutions resist enzymatic cleavage by dipeptidyl peptidase-4, and a fatty diacid side chain attached through a linker promotes binding to serum albumin. That albumin binding slows renal clearance and extends the circulating half-life from minutes to approximately one week. The structural changes are well established in the published literature. Whether the same modifications affect receptor signalling bias in ways that matter clinically remains an open question.
Post-translational modification (PTM) isoforms are easily detected on 2D gels. Indeed, phosphorylation replaces neutral hydroxyl groups on serines, threonines, or tyrosines with negatively charged phosphates with pKs near 1.2 and 6.5. Thus, below pH 5.5, phosphates add a single negative charge; near pH 6.5, they add 1.5 negative charges; above pH 7.5, they add 2 negative charges. The relative amount of each isoform can also easily and rapidly be determined from staining intensity on 2D gels. In some very specific cases, the detection of the phosphorylation as a shift in the protein's electrophoretic mobility is possible on simple 1-dimensional SDS-PAGE gels, as it is described for instance for a transcriptional coactivator by Kovacs et al. Strong phosphorylation-related conformational changes (that persist in detergent-containing solutions) are thought to underlie this phenomenon. Most of the phosphorylation sites for which such a mobility shift has been described fall in the category of SP and TP sites (i.e. a proline residue follows the phosphorylated serine or threonine residue). Large-scale mass spectrometry analyses have been used to determine sites of protein phosphorylation. Dozens of studies have been published, each identifying thousands of sites, many of which were previously undescribed. Mass spectrometry is ideally suited for such analyses using HCD or ETD fragmentation, as the addition of phosphorylation results in an increase in the mass of the protein and the phosphorylated residue.
Both sides agreed to build a "constructive strategic and stable relationship between China and the United States based on respect, fairness, and equality." Both sides agreed to support each other in successfully hosting the APEC Leaders' Informal Meeting and the G20 Leaders' Summit. The two heads of state expressed their intention to attend the meetings hosted by the other. The two heads of state agreed that Iran should uphold its commitment not to develop nuclear weapons and that no country or organization should impose tolls on international waterways. The two heads of state recalled that China and the United States were allies in World War II and fought side by side to win the war. The two heads of state acknowledged the positive role of the China–US trade consultation mechanism and the results of the consultations between the two trade teams, including the establishment and advancement of mechanisms such as the Council of Trade, the reaching of a $30 billion reciprocal tariff reduction arrangement, and the extension of the Kuala Lumpur trade consultation results, and instructed that these be implemented. Cooperation between Chinese and American drug enforcement agencies has yielded visible results. Recently, the two sides have worked closely together to crack multiple cases involving new psychoactive substances and precursor chemicals, arresting dozens of suspects in both countries. Both sides agreed to establish a China-US artificial intelligence dialogue to exchange views on the risks and benefits of AI. The next dialogue will be held in November this year.
Autolytic debridement is the use of moist dressings to promote autolysis with the body's own enzymes and white blood cells. This is a slow process, but mostly painless, and is most effective in individuals with a properly functioning immune system. Biological debridement, or maggot debridement therapy, is the use of medical maggots to feed on necrotic tissue and therefore clean the wound of excess bacteria. Although this fell out of favor for many years, in January 2004, the FDA approved maggots as a live medical device. Chemical debridement, or enzymatic debridement, is the use of prescribed enzymes that promote the removal of necrotic tissue. Mechanical debridement is the use of debriding dressings, whirlpool or ultrasound for slough in a stable wound. Surgical debridement, or sharp debridement, is the fastest method, as it allows a surgeon to quickly remove dead tissue.
King Pellam, wounded by Balin (as in the Post-Vulgate). In the Vulgate's clearer Grail lineage, Pelles is the son of Pellehan and is wounded in a separate accident, while in the Post-Vulgate Pelles and Pellehan are brothers. The further step of mistaking them as the same character is understandable; Malory confuses the brothers Ywain and Ywain the Bastard, whom he eventually regards as the same character, after treating them as separate. King Pelles, grandfather of Galahad, described as "the maimed king". In one passage, he is explicitly identified with Pellam; in another, he is said to have suffered his wound under different circumstances. King Pescheour (or Petchere), lord of the Grail Castle, who never appears (at least, not under that name). He owes his existence to a mistake by Malory, who took the Old French roy peschour ("Fisher King", a phrase that Malory never otherwise uses) for a name rather than an epithet. Nevertheless, Malory treats him as distinct from Pelles. An anonymous, bedridden Maimed King, healed by Galahad at the climax of the Grail Quest. He is distinct from Pelles, who has just been sent out of the room, and who is, anyway, at least mobile. In addition, there is King Pellinore, Perceval's father (in other versions of the legend, Perceval is related to the Grail Kings line). It appears that Malory intended to have one Maimed King who was wounded by Balin and suffered until healed by his grandson Galahad, but he never successfully reconciled his sources.
The Neanderthals were the first human species to permanently occupy Europe. While pre-Neanderthals are mostly identified around Western Europe, classic Neanderthals are recorded across Europe as well as Southwest and Central Asia, up to the Altai Mountains in southern Siberia. Pre- and early Neanderthals seem to have continuously occupied only France, Spain, and Italy, although some appear to have moved out of this "core-area" to form temporary settlements eastward (without leaving Europe). Nonetheless, southwestern France has the highest density of sites for pre- and classic Neanderthals. The southernmost find was recorded at Shuqba Cave, Palestine; reports of Neanderthals from the North African Jebel Irhoud and Haua Fteah have been reidentified as H. sapiens. Their easternmost presence is recorded at Denisova Cave, Siberia 85°E; the southeast Chinese Maba Man, a skull, shares several physical attributes with Neanderthals, although these may be the result of convergent evolution rather than Neanderthals extending their range to the Pacific Ocean. The northernmost bound is generally accepted to have been 55°N, with unambiguous sites known between 50–53°N, but this is difficult to assess because glacial advances destroy most human remains. Middle Palaeolithic artefacts have been found up to 60°N on the Russian plains, but these are more likely attributed to modern humans.
Sources: en.wikipedia.org
=== Greek philosophy === In Ancient Greece, Aristotle remarked on the importance of semen: "For Aristotle, semen is the residue derived from nourishment, that is of blood, that has been highly concocted to the optimum temperature and substance. This can only be emitted by the male as only the male, by nature of his very being, has the requisite heat to concoct blood into semen." According to Aristotle, there is a direct connection between food and semen: "Sperms are the excretion of our food, or to put it more clearly, as the most perfect component of our food." The connection between food and physical growth, on the one hand, and semen, on the other, allows Aristotle to warn against "engag[ing] in sexual activity at too early an age ... [since] this will affect the growth of their bodies. Nourishment that would otherwise make the body grow is diverted to the production of semen.
== SAR and the SAR paradox == The basic assumption for all molecule-based hypotheses is that similar molecules have similar activities. This principle is also called Structure–Activity Relationship (SAR). The underlying problem is therefore how to define a small difference on a molecular level, since each kind of activity, e.g. reaction ability, biotransformation ability, solubility, target activity, and so on, might depend on another difference. Examples were given in the bioisosterism reviews by Patanie/LaVoie and Brown. In general, one is more interested in finding strong trends. Created hypotheses usually rely on a finite number of chemicals, so care must be taken to avoid overfitting: the generation of hypotheses that fit training data very closely but perform poorly when applied to new data. The SAR paradox refers to the fact that it is not the case that all similar molecules have similar activities.
=== 13 January === At least 120 people were killed by shelling in western Omdurman. The Merowe Dam power station was damaged by RSF drones, causing a fire at the facility and power outages as far as Shendi, Port Sudan, Atbara and Omdurman. The SAF retook Karkaraia and Hajar al-Jawad, on the road between Dalang and Kadugli in South Kordofan, from the SPLM-N (al-Hilu). Thirteen people were killed by the SAF and allied militias in an attack on the informal settlement of Kambo Tayba in Gezira State.
excess exudate is delaying healing, infected exudate is present, there is contamination by a foreign body including dirt and bacteria devitalised tissue (slough and necrosis) is present. Wound cleansing is often undertaken as a ritual exercise rather than as an evidence-based activity. However, it has a role to play in all four domains of the WBP model. Wounds that are 'clean' and progressing do not require extraneous cleansing.
Polycystic Ovary Syndrome (PCOS) is a diverse condition characterized by the presence of either clinical or biochemical hyperandrogenism together with dysfunction in ovulation. The prevalence of this syndrome varies significantly, ranging from 6 to 15% in the general population. The metabolic characteristic of women with PCOS is the presence of hyperandrogenism and insulin resistance. Women with Polycystic Ovary Syndrome (PCOS) are frequently obese and tend to rely on assisted reproductive technologies more frequently than women who do not have this diagnosis.
Sources: en.wikipedia.org
== Further reading == Marshall JD, Beck S, Maffei P, Naggert JK (2007). "Alström syndrome". Eur. J. Hum. Genet. 15 (12): 1193–202. doi:10.1038/sj.ejhg.5201933. PMID 17940554. Alfonso Ortigado., et al. "Semaglutide in Alström Syndrome: An Improvement in the Natural Course of Cardiomyopathy". EC Paediatrics 14.7 (2025): 01-07. Berkower C. Voice of the Patient Report [Internet]. Alstrom Syndrome International; 2022 [cited 2024 Aug 22]. Available from: https://www.alstrom.org/wp-content/uploads/2023/05/ASI-EL-PFDD_FINAL_8May23.pdf Knorz VJ, Spalluto C, Lessard M, Purvis TL, Adigun FF, Collin GB, Hanley NA, Wilson DI, Hearn T (2010): Centriolar association of ALMS1 and likely centrosomal functions of the ALMS motif-containing proteins C10orf90 and KIAA1731. Mol Biol Cell (21):3617-3629. Koc E, Bayrak G, Suher M, Ensari C, Aktas D, Ensari A (2006): Rare case of Alstrom syndrome without obesity and with short stature, diagnosed in adulthood. Nephrology11(2):81-84. Roy A, Patel L, Yuan M, O'Shea C, Alvior AMB, Charalambides M, Moxon D, Baig S, Bunting KV, Gehmlich K, Geberhiwot T, Steeds RP. Defining the cardiovascular phenotype of adults with Alström syndrome. Int J Cardiol. 2024 Aug 15;409:132212. doi: 10.1016/j.ijcard.2024.132212. Epub 2024 May 26. PMID 38806112.
In this process, a ligand is immobilized on the dextran surface of the SPR crystal. Through a microflow system, a solution with the analyte is injected over the ligand-covered surface. The binding of the analyte to the ligand causes an increase in the SPR signal (expressed in response units, RU). Following the association time, a solution without the analyte (typically a buffer) is introduced into the microfluidics to initiate the dissociation of the bound complex between the ligand and analyte. As the analyte dissociates from the ligand, the SPR signal decreases. From these association ('on rate', ka) and dissociation rates ('off rate', kd), the equilibrium dissociation constant ('binding constant', KD) can be calculated. The detected SPR signal is a consequence of the electromagnetic 'coupling' of the incident light with the surface plasmon of the gold layer. This interaction is particularly sensitive to the characteristics of the layer at the gold–solution interface, which is usually just a few nanometers thick. When substances bind to the surface, it alters the way light is reflected, causing a change in the reflection angle, which can be measured as a signal in SPR experiments. One common application is measuring the kinetics of antibody-antigen interactions.
=== Bow–Bro === E. J. Bowen (1898–1980), English physical chemist known for research into fluorescence Humphry Bowen (1929–2001), English analytical chemist known for radioisotopes and trace elements Paul D. Boyer (1918–2018), American biochemist known for studying the biosynthesis of adenosine triphosphate (ATP), 1997 Nobel Prize in Chemistry Robert Boyle (1627–1691), Irish-English pioneer of modern chemistry, best known for Boyle's law Henri Braconnot (1780–1855), French chemist who worked on plant chemistry and discovered chitin and pectin Henning Brand (c. 1630–c.1692 or c. 1710), German alchemist, who accidentally discovered phosphorus while searching for the "philosopher's stone" Mary Bidwell Breed (1870–1949), American chemist focusing on aromatic acids and the atomic mass of palladium Ronald Breslow (1931–2017), American organic chemist who designed and synthesized new molecules with interesting properties, such as the cyclopropenyl cation Alan Brisdon (21st century), British chemist known for Inorganic Spectroscopic Methods Johannes Nicolaus Brønsted (1879–1947), Danish chemist known for work on reaction kinetics, especially acid–base reactions Herbert C.
Robert Schleip (born 1954) is a German psychologist, human biologist and author, best known for his work in the field of fascia. He serves as the director of the Fascia Research Group, a research collaboration between the University of Ulm and the Technical University of Munich. Schleip is also the founding director of the Fascia Research Society, the research director of the European Rolfing Association and vice president of the Ida P. Rolf Research Foundation. He is involved in the alternative medicine field of rolfing.
Sources: en.wikipedia.org
Long-term storage is usually at minus 20 to minus 80 degrees Celsius in a sealed, desiccated container. Working aliquots can be held briefly at 2 to 8 degrees Celsius.
Repeated temperature cycling can promote aggregation and peptide degradation. Dividing material into single-use aliquots limits this risk.
Mass spectrometry is commonly used to confirm molecular mass and detect structural modifications. It is often paired with chromatographic purity assessment.
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.