This is a working overview of deamidation, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-02-25 and is reviewed periodically as new material appears.
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.
Pharmacological activity arises from agonism at the glucagon-like peptide-1 receptor, a G protein-coupled receptor expressed in the pancreas, the gastrointestinal tract, and the brainstem. Receptor activation raises intracellular cyclic adenosine monophosphate and enhances insulin release in a glucose-dependent manner, an effect that diminishes when blood glucose concentration is low. Other effects include slowed gastric emptying and hypothalamic satiety signalling. These pathways are described well. Receptor desensitisation rates across tissues, relative to the endogenous hormone, are still under investigation, and reported findings differ between laboratories.
Reversed-phase high-performance liquid chromatography is widely used to assess purity and to separate the parent peptide from related substances. Mass spectrometry confirms identity and can resolve modifications that differ by a few daltons. Size-exclusion chromatography detects dimers and higher aggregates, which are relevant to both stability and immunogenicity questions. Peptide mapping with enzymatic digestion locates specific modifications along the sequence. Circular dichroism provides a secondary-structure profile, although it gives limited information about local conformational changes.
Quality control for peptide material focuses on identity, purity, content and the profile of impurities. Common degradants include deamidated and oxidised forms, plus aggregates formed during storage or handling. Forced degradation studies under heat, light, acid and peroxide help define which conditions accelerate change and which analytical methods detect it. Limits for individual impurities are set by pharmacopoeial monographs or manufacturer specifications. How much a given impurity affects biological activity is often uncertain, and conclusions may depend on the assay used.
Solid peptide material is generally kept at reduced temperature to limit degradation. Short-term storage at 2 to 8 degrees Celsius is common, while longer archival storage at minus 20 degrees Celsius or below is typical for lyophilised powder. Vials should remain sealed and protected from light, because ultraviolet exposure can oxidise susceptible residues. Repeated freeze-thaw cycles are avoided, as they promote aggregation and loss of soluble material. Solutions are less stable than solids and are usually prepared close to the time of use.
| Property | Value | Notes |
|---|---|---|
| Molecular class | 31-amino-acid peptide | Modified glucagon-like peptide-1 analogue |
| Molecular mass | approximately 4114 Da | Calculated for the free peptide backbone |
| Appearance | white to off-white powder | Typical of purified lyophilised peptide batches |
| Solubility class | freely soluble in water | Aqueous solubility improves at slightly alkaline pH |
| Typical storage | -20 degrees Celsius, dry, dark | Protect from repeated freeze-thaw cycles |
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.
Stability studies focus on deamidation of asparagine and glutamine residues, oxidation of methionine, and aggregation into higher-order species. The fatty acid side chain adds susceptibility to oxidative change and can promote self-association at high concentration. Lyophilised material is comparatively robust when kept cold and dry, while aqueous solutions require refrigeration and protection from light. Forced degradation experiments under heat, acid, base, and peroxide conditions establish the specificity of each analytical method. Which degradation route dominates under real storage conditions depends on the formulation and stays formulation-specific.
Handling guidance for research quantities calls for single-use aliquots, an inert atmosphere where practical, and avoidance of repeated freeze-thaw cycles that accelerate aggregation. Certificates of analysis typically report purity by peak area, water content, counter-ion identity, and residual solvent levels. In the scientific literature the compound is usually described by its full amino acid sequence, its registry number, or its structural class rather than by any proprietary label. Reporting standards vary between journals, and reviewers increasingly request raw chromatograms alongside tabulated purity figures. Whether current purity thresholds are adequate for every experimental context is debated.
Reversed-phase high-performance liquid chromatography with ultraviolet detection is the dominant approach for peptide purity assessment, usually paired with mass spectrometry to confirm molecular mass and sequence. Peptide mapping by enzymatic digestion and tandem mass spectrometry locates modifications such as deamidation and oxidation. Quantitation in plasma matrices can be performed by LC-MS/MS after solid-phase extraction. Method validation follows general guidance on accuracy, precision, linearity, and limits of detection. Comparability of results between laboratories, when no shared reference standard is available, remains an open question.
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.
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.
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.
In the same way that diatoms can regulate the fatty acid composition within their plastid membranes, they can also regulate the plasma membranes surrounding each cell. As temperatures decrease, membranes become less fluid. Both bacteria and sea ice diatoms can alter the fatty acid composition within their membranes to include more unsaturated fatty acids, which allow the plasma membrane to maintain fluidity in extreme cold temperatures.
== History == In 1822, Baron Charles Cagniard de la Tour discovered the critical point of a substance in his famous cannon barrel experiments. Listening to discontinuities in the sound of a rolling flint ball in a sealed cannon filled with fluids at various temperatures, he observed the critical temperature. Above this temperature, the densities of the liquid and gas phases become equal and the distinction between them disappears, resulting in a single supercritical fluid phase. Recently, a significant effort has been devoted to investigation of various properties of supercritical fluids. Supercritical fluids have found application in a variety of fields, ranging from the extraction of floral fragrance from flowers to applications in food science such as creating decaffeinated coffee, functional food ingredients, pharmaceuticals, cosmetics, polymers, powders, bio- and functional materials, nanomaterials, natural products, biotechnology, fossil and bio-fuels, microelectronics, energy and environment. There have also been efforts to use supercritical fluids to improve effectiveness of sensors. The development of new experimental methods and improvement of existing ones continues to play an important role in this field, with recent research focusing on dynamic properties of fluids.
Less than 5% of the power consumed by a typical tungsten incandescent light bulb is converted into visible light, with most of the rest being emitted as invisible infrared radiation. Some applications make use of the emitted infrared radiation, such as heat lamps in incubators, lava lamps, Edison effect bulbs, and the Easy-Bake Oven toy. Quartz envelope halogen infrared heaters are used for industrial processes such as paint curing and space heating. Light bulbs are rated by their luminous efficacy, which is the ratio of the amount of visible light emitted (luminous flux) to the electrical power consumed. Luminous efficacy is measured in lumens per watt (lm/W). The luminous efficiency of a source is defined as the ratio of its luminous efficacy to the maximum possible luminous efficacy, which is 683 lm/W. An ideal white light source could produce about 250 lumens per watt, corresponding to a luminous efficiency of 37%. For a given quantity of light, an incandescent light bulb consumes more power and emits more heat than most other types of electric light. In buildings where air conditioning is used, incandescent lamps' heat output increases load on the air conditioning system. While heat from lights will reduce the need to run a building's heating system, the latter can usually produce the same amount of heat at lower cost than incandescent lights. The chart below lists the luminous efficacy and efficiency for several types of incandescent bulb. A longer chart in luminous efficacy compares a broader array of light sources.
==== Juan Alberto Kessel Linares elected as Grand Master ==== Late in the day on March 24, Juan Alberto Kessel Linares was elected as the new Grand Master of the Grand Lodge of Cuba to replace Urquía Carreño. On March 30, a week after his appointment as Grand Master, Kessel Linares accused Urquía Carreño of having stolen an additional $2,360 in August 2023. The money, according to Kessel Linares, had been given to him by the serving Grand Treasurer at the time, Salvador Orestes Arango Troncoso. When Urquía Carreño was eventually asked about the money by Grand Secretary Misiel Hernández Peraza, Urquía Carreño allegedly informed him that the money was in the possession of the recently elected Grand Treasurer, Airam Cervera. Kessel Linares then revealed that the Grand Lodge had filed an official complaint with the National Revolutionary Police at the Zapata Police Station in Havana.
Sources: en.wikipedia.org
==== Low sex hormone levels ==== Clinical studies have consistently associated medical and recreational opioid use with hypogonadism (low sex hormone levels) in different sexes. The effect is dose-dependent. Most studies suggest that the majority (perhaps as much as 90%) of chronic opioid users develop hypogonadism. A 2015 systematic review and meta-analysis found that opioid therapy suppressed testosterone levels in men by about 165 ng/dL (5.7 nmol/L) on average, which was a reduction in testosterone level of almost 50%. Conversely, opioid therapy did not significantly affect testosterone levels in women. However, opioids can also interfere with menstruation in women by limiting the production of luteinizing hormone (LH). Opioid-induced hypogonadism likely causes the strong association of opioid use with osteoporosis and bone fracture, due to deficiency in estradiol. It also may increase pain and thereby interfere with the intended clinical effect of opioid treatment. Opioid-induced hypogonadism is likely caused by their agonism of opioid receptors in the hypothalamus and the pituitary gland. One study found that the depressed testosterone levels of heroin addicts returned to normal within one month of abstinence, suggesting that the effect is readily reversible and is not permanent. As of 2013, the effect of low-dose or acute opioid use on the endocrine system is unclear. Long-term use of opioids can affect the other hormonal systems as well.
== Side effects == The most common side effects associated with CEEs are vaginal yeast infections, vaginal spotting or bleeding, painful menses, and cramping of the legs. While there are some contradictory data, estrogen alone does not appear to increase the risk of coronary heart disease or breast cancer, unlike the case of estrogen in combination with certain progestins such as levonorgestrel or medroxyprogesterone acetate. Only a few clinical studies have assessed differences between oral CEEs and oral estradiol in terms of health parameters. Oral CEEs have been found to possess a significantly greater risk of thromboembolic and cardiovascular complications than oral estradiol (ORTooltip Odds ratio = 2.08) and oral esterified estrogens (ORTooltip Odds ratio = 1.78). However, in another study, the increase in venous thromboembolism risk with oral CEEs plus medroxyprogesterone acetate and oral estradiol plus norethisterone acetate was found to be equivalent (RRTooltip Relative risk = 4.0 and 3.9, respectively). As of present, there are no randomized controlled trials that would allow for unambiguous conclusions.
=== Tanning and early stuffing techniques === Preserving animal skins has been practiced throughout human history. For example, embalmed animals have been found with Egyptian mummies. In Tenochtitlan, the capital of the Aztec Empire, taxidermy was a common practice, not only for preserving animals, but also because it held a deep symbolic value within Aztec culture. Eagles had the most symbolic impact; a particular cut mark on an eagle's skull indicates its having received treatment to taxidermize it. An important find in the remains of Tenochtitlan is twelve golden eagles that were found near the monolith of the goddess Tlaltecuhtli. The eagles were found dressed with copper anklets and pectorals of wood on their chests. Through intricate ritual events with different objects, including the taxidermized eagle skulls, the people of Tenochtitlan believed that they could create a link between the earthly and the divine. Although embalming incorporates lifelike poses, it is not considered taxidermy. In the Middle Ages, crude examples of taxidermy were displayed by astrologers and apothecaries. The earliest methods of preservation of birds for natural history cabinets were published in 1748 by René-Antoine Ferchault de Réaumur in France. Techniques for mounting were described in 1752 by M. B. Stollas. There were several pioneers of taxidermy in France, Germany, Denmark, and England. For a while, clay was used to shape some of the soft parts, but this made specimens heavy. By the 18th century, a majority of towns had a tannery business.
Sources: en.wikipedia.org
C6H5HgCl + CCl2 → C6H5HgCCl3, reversed with heat. Organomercury halides react with hydride sources to give organomercury hydrides. Those compounds have an exceptionally weak C−Hg bond, and readily cleave to alkyl radicals.
== M == M13 phage - m7G(5')pppN diphosphatase - malformation - maltose-transporting ATPase - manganese-transporting ATPase - mannose-6-phosphate 6-reductase - mapping - marker - melanoma - melting - menaquinol oxidase (H+-transporting) - Johann Mendel - Mendelian inheritance - message - messenger RNA - metaphase - methylphenyltetrahydropyridine N-monooxygenase - methylsterol monooxygenase - methyltetrahydroprotoberberine 14-monooxygenase - microarray technology - microsatellite - MIMT1 - minusheet perfusion culture system - Mir-188 microRNA precursor family - Mir-615 microRNA precursor family - Mir-675 microRNA precursor family - missense mutation - mitochondrial DNA - mobility shift - molecular weight size marker - monoclonal antibody - monosaccharide-transporting ATPase - monosomy - morphine 6-dehydrogenase - mouse model - mRNA - multicistronic message - multicopy plasmid - multiple cloning site - multiple endocrine neoplasia, type 1 - mutation - myristoyl-CoA 11-(E) desaturase - myristoyl-CoA 11-(Z) desaturase -
== Function == The trachea's main function is to transport air to and from the lungs. It also helps to warm, humidify, and filter the air before it reaches the lungs. The trachea is made up of rings of cartilage, which help to keep it open and prevent it from collapsing. The inside of the trachea is lined with a mucous membrane, which produces mucus to help trap dirt and dust particles. The cilia, which are tiny hairs that line the mucous membrane, help to move the mucus and trapped particles up and out of the trachea.
Regulation of transcription can be broken down into three main routes of influence; genetic (direct interaction of a control factor with the gene), modulation interaction of a control factor with the transcription machinery and epigenetic (non-sequence changes in DNA structure that influence transcription).
Sources: en.wikipedia.org
It is a glucagon-like peptide-1 receptor agonist, often grouped with the incretin mimetics. Its backbone is modified from the human hormone to resist enzymatic degradation and to bind albumin. These two features distinguish it from the native peptide.
No. It shares high sequence identity but carries non-natural modifications that alter its stability and clearance. The naturally occurring hormone is broken down within minutes, while the synthetic analogue circulates far longer.
Attachment to serum albumin reduces renal filtration of the peptide and shields it from enzymatic breakdown. The consequence is a much longer interval between administrations than unmodified peptides allow. The precise contribution of binding affinity to overall duration is still being quantified.
Lower temperatures slow hydrolysis, oxidation and aggregation reactions that degrade the molecule over time. Lyophilised powder is more tolerant than solution, but both benefit from controlled conditions.