This is a working overview of GLP-1, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-03-16 and is reviewed periodically as new material appears.
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.
Peptides are sensitive to temperature, light, oxygen, and repeated freeze-thaw cycles. Semaglutide in dry form is generally held at refrigerated temperatures, while reconstituted solutions require a defined short-term storage window. Vials should be kept in secondary packaging to limit photodegradation, and exposure to alkaline conditions is avoided because it accelerates chemical degradation. Adsorption to glass and some plastics can reduce the measured concentration of dilute solutions, so low-binding polypropylene containers are preferred for analytical work. Each transfer step introduces a small risk of contamination, and closed handling practices reduce that risk.
Routine characterisation of the peptide relies on reversed-phase high-performance liquid chromatography, often paired with ultraviolet detection near 214 nanometres. Related substances such as deamidated, oxidised, and truncated sequences elute at characteristic positions and are quantified by area percentage. Electrospray ionisation mass spectrometry confirms the molecular mass and can resolve some closely related variants. Peptide mapping after enzymatic digestion provides sequence-level verification and is useful when a full identity profile is required. Method parameters such as column chemistry, gradient, and mobile-phase pH influence the separation and must be reported alongside results.
| 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 |
Lyophilized peptide material is typically stored at or below -20 °C, with -80 °C used for longer-term archives. Vials should remain sealed and desiccated because moisture promotes aggregation and hydrolysis. Repeated freeze-thaw cycles are avoided since they can alter peptide conformation and reduce recovery. Once reconstituted, solutions are generally kept at 2-8 °C and used within a defined window. Stability beyond those windows depends on buffer composition and concentration, and exact limits are product-specific rather than universal.
Identity and purity are assessed with reversed-phase high-performance liquid chromatography, which separates the peptide from related impurities by hydrophobicity. Mass spectrometry confirms molecular weight and detects truncation or modification products. Peptide mapping after enzymatic digestion verifies the amino acid sequence. Quantitation is often performed by LC-MS/MS or by immunoassay, and the two approaches can give different values because they measure different things. Method validation parameters such as accuracy, precision, and limit of quantitation are reported alongside results.
肽类的主要降解路径包括天冬酰胺脱酰胺、甲硫氨酸氧化、天冬氨酸异构化以及由 β-折叠驱动的聚集，这些反应对 pH 与缓冲液种类较为敏感。磷酸盐、丙二醇与苯酚等辅料会影响局部微环境与界面行为。强制降解研究借助高温、强光、氧化剂与极端 pH 暴露来预测产物谱。关于长期室温存放的数据相对有限，超出标签条件的稳定性仍属开放问题，需要在具体制剂中通过实时与加速试验加以确认。
容器与密封系统同样参与稳定性表现。硅油涂层、胶塞材质与顶空氧含量可能改变聚集速率与氧化水平。分析结果因此需要在完整包装形式下评估，而不能仅凭原料药数据推断。法规文件通常要求同时提交批次数据与代表性容器中的稳定性趋势。
This will invoke the component's search function, passing "your query" and "strict" as arguments. This type of invocation is well-suited for Ajax-enabled applications. ColdFusion 8 introduced the ability to serialize ColdFusion data structures to JSON for consumption on the client. The ColdFusion server will automatically generate documentation for a component if you navigate to its URL and insert the appropriate code within the component's declarations. This is an application of component introspection, available to developers of ColdFusion components. Access to a component's documentation requires a password. A developer can view the documentation for all components known to the ColdFusion server by navigating to the ColdFusion URL. This interface resembles the Javadoc HTML documentation for Java classes.
== History == Use of castor oil as a laxative is attested to in the c. 1550 BC Ebers Papyrus, and it was in use several centuries earlier. Midwifery manuals from the 19th century recommended castor oil and 10 drops of laudanum for relieving "false pains".
=== Administrative history === Wilmslow was an ancient parish in the Macclesfield Hundred of Cheshire. The parish was subdivided into four townships, called Bollin Fee, Chorley, Fulshaw, and Pownall Fee. The town centre and the parish church of St Bartholomew's lay in the Bollin Fee township. From the 17th century onwards, parishes were gradually given various civil functions under the poor laws, in addition to their original ecclesiastical functions. In some cases, including Wilmslow, the civil functions were exercised by each township separately rather than the parish as a whole. In 1866, the legal definition of 'parish' was changed to be the areas used for administering the poor laws, and so the townships each became separate civil parishes, which therefore diverged from the ecclesiastical parish. In 1862, a Chorley local government district was created, governed by an elected local board. The district covered the eastern part of the Chorley township, plus small adjoining parts of the Bollin Fee and Fulshaw townships. The Chorley district was renamed Alderley Edge in 1894. In 1878, a separate Wilmslow local government district was created covering the remainder of Bollin Fee and Fulshaw, plus Pownall Fee apart from the area north of the River Bollin and River Dean; the excluded area north of the rivers contained the hamlet of Styal. Local government districts were reconstituted as urban districts under the Local Government Act 1894.
Sources: en.wikipedia.org
Over the next thirty years many calibration curves were published using a variety of methods and statistical approaches. These were superseded by the IntCal series of curves, beginning with IntCal98, published in 1998, and updated in 2004, 2009, 2013, and 2020. The improvements to these curves are based on new data gathered from tree rings, varves, coral, plant macrofossils, speleothems, and foraminifera. There are separate curves for the northern hemisphere (IntCal20) and southern hemisphere (SHCal20), as they differ systematically because of the hemisphere effect. The continuous sequence of tree-ring dates for the northern hemisphere goes back to 13,910 BP as of 2020, and this provides close to annual dating for IntCal20 much of the period, reduced where there are calibration plateaus, and increased when short term 14C spikes due to Miyake events provide additional correlation. Radiocarbon dating earlier than the continuous tree ring sequence relies on correlation with more approximate records. SHCal20 is based on independent data where possible and derived from the northern curve by adding the average offset for the southern hemisphere where no direct data was available. There is also a separate marine calibration curve, MARINE20. For a set of samples forming a sequence with a known separation in time, these samples form a subset of the calibration curve. The sequence can be compared to the calibration curve and the best match to the sequence established. This "wiggle-matching" technique can lead to more precise dating than is possible with individual radiocarbon dates.
=== Non-flammable electrolyte === In 2023, most commercial Li-ion batteries employed alkylcarbonate solvents to assure the formation solid electrolyte interface on the negative electrode. Since such solvents are readily flammable, there has been active research to replace them with non-flammable solvents or to add fire suppressants. Another source of hazard is hexafluorophosphate anion, which is needed to passivate the negative current collector made of aluminium. Hexafluorophosphate reacts with water and releases volatile and toxic hydrogen fluoride. Several strategies have been explored for developing non-flammable Li-ion battery electrolytes. One approach uses fluorinated (co-)solvents, such as methyl-(2,2,2-trifluoroethyl)-carbonate (FEMC) or methyl-3,3,3-trifluoropropionate (MTFP). Another approach uses fluorinated anions, such as lithium bis(trifluoromethanesulfonyl)imide or lithium difluoro(oxalato)borate in high concentrations.
The Rhodesians of the Cape Town Highlanders patrolled nightly around the village of Casigno for the next three months. Some of the tank crews, including the Rhodesians of the Special Service Battalion, were temporarily reassigned to infantry duties to assist in these patrols. Many of the Rhodesians had never seen snow before, but on the whole they adapted well, taking up winter sports such as skiing during time off duty. The Rhodesians of the Special Service Battalion received new, more heavily armed tanks in November–December 1944. In February 1945 the 6th Division was relieved by the American 1st Armoured Division and moved to Lucca, 15 kilometres (9.3 mi) north of Pisa, for rest and reorganisation. The Rhodesian Anti-Tank Battery was refitted with M10 tank destroyers. The Spitfires of No. 237 Squadron, meanwhile, took part in assaults on German transport in the Po Valley around Parma and Modena.
Sources: en.wikipedia.org
=== Without a hydrogen on the α-carbon === All proteinogenic amino acids have at least one hydrogen on the α-carbon. Glycine has two hydrogens, and all others have one hydrogen and one side-chain. Replacement of the remaining hydrogen with a larger substituent, such as a methyl group, distorts the protein backbone. In some fungi α-aminoisobutyric acid is produced as a precursor to peptides, some of which exhibit antibiotic properties. This compound is similar to alanine, but possesses an additional methyl group on the α-carbon instead of a hydrogen. It is therefore achiral. Another compound similar to alanine without an α-hydrogen is dehydroalanine, which possesses a methylene sidechain. It is one of several naturally occurring dehydroamino acids.
=== Internal standards === A series of internal standards contain the same concentration of a chemical called the internal standard and different concentrations of the analyte. The internal standard should be chemically similar to the analyte, so that the two receive the same treatment during measurement. Internal standards are used to correct for loss of analyte during sample preparation, for example when the analyte is in a volatile solvent. If both the internal standard and the analyte lose solvent proportionally, their signals will remain identical and the ratio of their signals can be measured. Plotting the ratio of the analyte signal to the internal standard signal against the analyte concentration results in a calibration curve. Similar to the external calibration curve, the internal calibration curve also allows to calculate the concentration of analyte in an unknown sample.
Households comprising couples with or without children make up 51 percent of all households; 8.7 percent of households are single-parent households, 2.9 percent are multigenerational households, and 29.3 percent are single-person households.
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.
Different techniques detect different classes of impurities, so a single number does not describe a sample completely. Reversed-phase chromatography resolves related peptides well but can miss inorganic salts, while mass spectrometry confirms mass without quantifying everything present. Comparing results requires knowing which method was used and how it was validated.