fatty diacid chain 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 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Receptor activation raises intracellular cyclic AMP through Gs coupling, which promotes glucose-dependent insulin release and suppresses glucagon secretion when blood glucose is elevated. Effects outside the pancreas include slower gastric emptying and altered appetite signalling in the hypothalamus and hindbrain. The relative contribution of each tissue to overall metabolic outcomes remains an area of active investigation. Central mechanisms in particular are inferred mainly from animal models and indirect human measures rather than direct observation.
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.
| 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 |
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。
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.
When the news of the curative properties of penicillin broke, Fleming revelled in the publicity. Journalists told a familiar story of a lone British scientist and a serendipitous discovery. The British medical historian Bill Bynum wrote:The discovery and development of penicillin is an object lesson of modernity: the contrast between an alert individual (Fleming) making an isolated observation and the exploitation of the observation through teamwork and the scientific division of labour (Florey and his group). The discovery was old science, but the drug itself required new ways of doing science. In 1943, the Nobel committee received a single nomination for the Nobel Prize in Physiology or Medicine for Fleming and Florey from the British biochemist Rudolph Peters. The secretary of the Nobel committee, Göran Liljestrand, made an assessment of Fleming and Florey in the same year, but little was known about penicillin in Sweden at the time, and he concluded that more information was required. The following year, there was one nomination for Fleming alone and one for Fleming, Florey and Chain. Liljestrand and Nanna Svartz considered their work, and while both judged Fleming and Florey equally worthy of a Nobel Prize, the Nobel committee was divided, and decided to award the prize that year to Joseph Erlanger and Herbert S. Gasser instead. In 1945 there were a large number of nominations for Florey and Fleming or both, and one for Chain, from Liljestrand, who nominated all three.
==== Predictive Low Glucose Suspend (PLGS) ==== A step forward from threshold suspend systems, predictive low glucose suspend (PLGS) systems use a mathematical model to extrapolate predicted future blood sugar levels based on recent past readings from a CGM. This allows the system to reduce or halt insulin delivery prior to a predicted hypoglycemic event.
=== Phase 2 === Abatacept (Orencia) – injection – alopecia areata – T cell activation inhibitor Amlitelimab (KY-1005, SAR-445229) – subcutaneous injection – alopecia areata – OX40 ligand inhibitor BAY-1158061 (HMI-115) – subcutaneous injection – alopecia – prolactin receptor monoclonal antibody (prolactin receptor inhibitor) Bempikibart (ADX-914, BMS-986265) – subcutaneous injection – alopecia areata – CRLF2 protein antagonist, interleukin 7 receptor α subunit inhibitor Bimatoprost (Lumigan) – topical – alopecia – prostaglandin F receptor agonist (prostaglandin F2α analogue) Botulinum toxin A (Xeomin; incobotulinum toxin A) – intradermal – alopecia – acetylcholine release inhibitor and neuromuscular blocking agent CKD-498 – oral – alopecia – undefined mechanism of action Daxdilimab (HZN-7734; MEDI-7734; VIB-7734) – oral – alopecia areata – anti-ILT7 human monoclonal antibody/dendritic cell inhibitor Delgocitinib (Anzupgo, Corectim; JTE-052, LEO-124249, LP-0133) – unknown – alopecia areata – Janus kinase inhibitor Deucravacitinib (Sotyktu; BMS-986165) – oral – alopecia areata – TYK2 kinase inhibitor Finasteride/latanoprost/minoxidil (TH-07; Triple Hair) – topical – alopecia – combination drug/multiple mechanisms of action FOL-005 (osteopontin-derived peptide) – intradermal – alopecia – undefined mechanism of action GT-20029 (AR-PROTAC) – topical – alopecia – androgen receptor degradation enhancer KL-130008 – oral – alopecia areata – Janus kinase inhibitor Latanoprost (DLQ01; DLQ-01) – topical – androgenic alopecia – prostaglandin F receptor agonist (prostaglandin F2α analogue) NXC-736 – oral – alopecia areata – sphingosine 1 phosphate receptor antagonist Rezpegaldesleukin (Rezpeg; LY-3471851, NKTR-358) – unknown – alopecia areata – interleukin-2 conjugate/modulator RK-023 (nobiprostolan) – topical – alopecia, hypotrichosis – undefined mechanism of action (prostaglandin F2α analogue) Rosnilimab (ANB-030) – subcutaneous injection – alopecia areata – programmed cell death 1 receptor agonist Ruxolitinib (Jakafi, Jakavi, Opzelura; INCB-018424) – topical – alopecia areata – Janus kinase 1 inhibitor, Janus kinase 2 inhibitor SIS-302-AA – unspecified – alopecia areata – undefined mechanism of action Suvomipic (PP405; PP-405; JXL069; JXL-069) – topical – alopecia – mitochondrial pyruvate carrier (MPC) inhibitor SYHX-1901 – oral – alopecia areata – Janus kinase inhibitor, Syk kinase inhibitor TDM-105795 (CU-40101) – topical – alopecia – thyroid hormone receptor agonist
Sources: en.wikipedia.org
=== Splitting monolayer carbon allotropes === Graphene can be created by opening carbon nanotubes by cutting or etching. In one such method, multi-walled carbon nanotubes were cut open in solution by action of potassium permanganate and sulfuric acid. In 2014, carbon nanotube-reinforced graphene was made via spin coating and annealing functionalized carbon nanotubes. Another approach sprays buckyballs at supersonic speeds onto a substrate. The balls cracked open upon impact, and the resulting unzipped cages then bond together to form a graphene film.
=== Coronary heart disease risk === Arterial damage results from white blood cell invasion and inflammation within the wall. CRP is a general marker for inflammation and infection, so it can be used as a very rough proxy for heart disease risk. Since many things can cause elevated CRP, this is not a very specific prognostic indicator. Nevertheless, a level above 2.4 mg/L has been associated with a doubled risk of a coronary event compared to levels below 1 mg/L; however, the study group in this case consisted of patients who had been diagnosed with unstable angina pectoris; whether elevated CRP has any predictive value of acute coronary events in the general population of all age ranges remains unclear. Currently, C-reactive protein is not recommended as a cardiovascular disease screening test for average-risk adults without symptoms. The American Heart Association and U.S. Centers for Disease Control and Prevention have defined risk groups as follows:
== Terminology == Pyrolysis is one of the various types of chemical degradation processes that occur at higher temperatures (above the boiling point of water or other solvents). It differs from other processes like combustion and hydrolysis in that it usually does not involve the addition of other reagents such as oxygen (O2, in combustion) or water (in hydrolysis). Pyrolysis produces solids (char), condensable liquids (heavy and light oils, and tar), and non-condensable gasses. Pyrolysis is different from gasification. In the chemical process industry, pyrolysis refers to a partial thermal degradation of carbonaceous materials that takes place in an inert (oxygen free) atmosphere and produces both gases, liquids and solids. The pyrolysis can be extended to full gasification that produces mainly gaseous output, often with the addition of e.g. water steam to gasify residual carbonic solids, see Steam reforming.
== Legacy == His career in the industry is acknowledged through the "Frank Vale Award" which is presented annually at the Refrigerated Warehouse and Transport Association of Australia (RWTA) Conference and Exhibition to an outstanding young achiever.
Sources: en.wikipedia.org
Members of both the Democratic & Republican parties who opposed Trump's border control policies regarded the border wall as unnecessary or undesirable, arguing that other measures would be more effective at reducing illegal immigration than building a wall, including tackling the economic issues that lead to immigration being a relevant issue altogether, border surveillance or an increase in the number of customs agents. Additionally, in August 2020, the United States constructed 3.8 km of short cable fencing along the border between Abbotsford, British Columbia, and Whatcom County, Washington. Border walls have formed a major component of European border control policy following the European migrant crisis. The walls at Melilla and at Ceuta on Spain's border with Morocco are designed to curtail refugees' and migrants' ability to enter the European Union via the two Spanish cities on the Moroccan coast. Similar measures have been taken on the Schengen area's borders with Turkey in response to the refugee crisis in Syria. The creation of the European Union's collective border security organisation, Frontex, is another aspect of the bloc's growing focus on border security. Within the Schengen Area, border security has become an especially prominent priority for the Hungarian government under right-wing strongman Viktor Orbán. Similarly, Saudi Arabia has begun construction of a border barrier or fence between its territory and Yemen to prevent the unauthorized movement of people and goods.
Petri dish A shallow, transparent plastic or glass dish, usually circular and covered with a lid, which is widely used in biology laboratories to hold solid or liquid growth media for the purpose of culturing cells. They are particularly useful for adherent cultures, where they provide a flat, sterile surface conducive to colony formation from which scientists can easily isolate and identify individual colonies.
is the elementary charge. The most important difference is that, in the absence of field line-breaking, the magnetic field is tied to the electrons rather than to the bulk fluid. Electron MHD Electron magnetohydrodynamics (EMHD) describes small-scale plasmas in which electron motion is much faster than the ion motion. The main effects are changes in conservation laws, additional resistivity, and the importance of electron inertia. Many effects of Electron MHD are similar to those of two-fluid MHD and Hall MHD. EMHD is especially important for z-pinches, magnetic reconnection, ion thrusters, neutron stars, and plasma switches. Collisionless MHD is also used for collisionless plasmas. In that case, the MHD equations are derived from the Vlasov equation. Reduced By using a multiscale analysis, the (resistive) MHD equations can be reduced to a set of four closed scalar equations. This allows for, among other things, more efficient numerical calculations.
With the encouragement of Ollendorff (promising that a US organization called "The Friends of the Technion" would support Feher's studies), he applied for 50 universities in the US, and only two were willing to accept him. He could not afford the voyage to US so he started a small production line for devices with piezoelectric crystals, mainly microphones. In December 1946 he arrived to New York, where he realized that "Friends of the Technion" would not fund his degree. With poor means he attended the University of California, Berkeley, where he received his bachelor's degree in engineering physics (1950), master's degree in electrical engineering (1951) and doctorate (1954).
When atomic mass is shown, it is usually the weighted average of naturally occurring isotopes; but if no isotopes occur naturally in significant quantities, the mass of the most stable isotope usually appears, often in parentheses. In the standard periodic table, the elements are listed in order of increasing atomic number. A new row (period) is started when a new electron shell has its first electron. Columns (groups) are determined by the electron configuration of the atom; elements with the same number of electrons in a particular subshell fall into the same columns (e.g. oxygen, sulfur, and selenium are in the same column because they all have four electrons in the outermost p-subshell). Elements with similar chemical properties generally fall into the same group in the periodic table, although in the f-block, and to some respect in the d-block, the elements in the same period tend to have similar properties, as well. Thus, it is relatively easy to predict the chemical properties of an element if one knows the properties of the elements around it. Today, 118 elements are known, the first 94 of which are known to occur naturally on Earth. The remaining 24, americium to oganesson (95–118), occur only when synthesized in laboratories. Of the 94 naturally occurring elements, 83 are primordial and 11 occur only in decay chains of primordial elements.
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.