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 2025-07-29 and is reviewed periodically as new material appears.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Acylated GLP-1 receptor agonist | 31-residue synthetic peptide |
| Molecular formula | C187H291N45O59 | established for the free peptide |
| Appearance | White to off-white powder | as supplied before formulation |
| Solubility | Freely soluble in water | aqueous buffers near neutral pH |
| Typical storage | 2 to 8 degrees Celsius, protected from light | powder and solution forms differ in shelf life |
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.
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.
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.
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.
=== Use in crime === The Z-drugs, including zolpidem, have been used as date rape drugs. Zolpidem is available by prescription, and broadly prescribed unlike other date rape drugs: gamma-hydroxybutyrate (GHB), which is used to treat narcolepsy, or flunitrazepam (Rohypnol), which is only prescribed as a second-line choice for insomnia. Zolpidem can be detected in bodily fluids for 36 hours, though it may be possible to detect it by hair testing much later, which is due to the short elimination half-life of 2.5–3 hours. This use of the drug was highlighted during proceedings against Darren Sharper, who was accused of using the tablets he was prescribed to facilitate a series of rapes.
Predominantly, the "energy expenditure hormone" leptin is made by adipose cells, and is thus labeled fat cell-specific. In the context of its effects, the adjectives central, direct, and primary are not used interchangeably. In regard to the hormone leptin, central vs peripheral refers to the hypothalamic portion of the brain vs non-hypothalamic location of action of leptin; direct vs indirect refers to whether there is no intermediary, or there is an intermediary in the mode of action of leptin; and primary vs secondary is an arbitrary description of a particular function of leptin.
==== Pollution ==== Pollution, the presence of contaminants in an environment that causes adverse effects, could have been present as early as the Inca Empire. They used a lead sulfide flux in the smelting of ores, along with the use of a wind-drafted clay kiln, which released lead into the atmosphere and the sediment of rivers.
The relationship between the Druze and Christians in Israel has generally been marked by harmony and peaceful coexistence, with both communities living together in peace, harmony, and friendship. However, there have been rare clashes, including instances of violence by the Druze against Christians, such as the incident in 2005 in the town of town of Maghar. Druze and Christians in Israel participate in each other's cultural events, including births, weddings, funerals, and celebrations like the Christian festival of Mar Ilyas (Saint Elias) in Haifa. Additionally, many Druze students are enrolled in Christian schools across the Galilee and Haifa regions. Some Druze towns are situated near significant Christian holy sites, with the most prominent being the Catholic Muhraqa Monastery located 2 kilometres southeast of Daliyat al-Karmel, the largest Druze town in Israel, and marks the contest between prophet Elijah and the priests of Ba'al. It belongs to the Carmelite Order. In the predominantly Druze town of Hurfeish, there is the Church and House of Saint Mariam Baouardy. Interaction between Christians, including members of the Maronite, Eastern Orthodox, Melkite, and other churches, and the Unitarian Druze has resulted in the establishment of mixed villages and towns in Galilee region, Mount Carmel, and the Israeli-occupied portion of the Golan Heights. These include Abu Snan, Daliyat al-Karmel, Ein Qiniyye, Hurfeish, Isfiya, Kafr Yasif, Kisra-Sumei, Majdal Shams, Maghar, Peki'in, Rameh and Shefa-Amr, where more than 82,000 Druze and 30,000 Christians reside together.
Sources: en.wikipedia.org
The Golden Gate assembly protocol was defined by Engler et al. 2008 to define a DNA assembly method that would give a final construct without a scar sequence, while also lacking the original restriction sites. This allows the protein to be expressed without containing unwanted protein sequences which could negatively affect protein folding or expression. By using the BsaI restriction enzyme that produces a 4 base pair overhang, up to 240 unique, non-palindromic sequences can be used for assembly. Plasmid design and assembly In Golden Gate cloning, each DNA fragment to be assembled is placed in a plasmid, flanked by inward facing BsaI restriction sites containing the programmed overhang sequences. For each DNA fragment, the 3' overhang sequence is complementary to the 5' overhang of the next downstream DNA fragment. For the first fragment, the 5' overhang is complementary to the 5' overhang of the destination plasmid, while the 3' overhang of the final fragment is complementary to the 3' overhang of the destination plasmid. Such a design allows for all DNA fragments to be assembled in a one-pot reaction (where all reactants are mixed together), with all fragments arranged in the correct sequence. Successfully assembled constructs are selected by detecting the loss of function of a screening cassette that was originally in the destination plasmid. MoClo and Golden Braid The original Golden Gate Assembly only allows for a single construct to be made in the destination vector .
Gestation in bats ranges from around 40 days to eight months, correlating with the size of the species. In most bat species, females carry and give birth to a single pup per litter. A newborn bat pup can be up to 40 percent of the mother's weight, and the pelvic girdle of the female can expand during birth as the two halves are connected by a flexible ligament. Females typically give birth upright or horizontally, using gravity to make the process easier. The young emerges rear-first, possibly to prevent the wings from becoming tangled, and the female holds it in her wing and tail membranes. In many species, females give birth and raise their young in maternity colonies and may assist each other in birthing. Most of the care for a young bat comes from the mother, though in monogamous species, the father plays a role. Allo-suckling, where a female suckles another mother's young, occurs in several species. This may serve to increase colony size in species where females breed in their birth colonies. Young bats can fly after they develop their adult body dimensions and forelimb length. For the little brown bat, this occurs when they are eighteen days old. Weaning of young for most species takes place in under 80 days. The common vampire bat nurses its offspring beyond that, and young vampire bats achieve independence later in life than other species. This is probably due to the species's blood-based diet, as the female may not be able to feed on a nightly basis.
=== Less common === Confusion Irritability and aggression Psychomotor agitation Lack of motivation Increased libido Loss of libido Impaired motor function Impaired coordination Impaired balance Dizziness Cognitive impairments Hallucinations. Short-term memory loss Anterograde amnesia (common with higher doses) Some users report hangover-like symptoms of drowsiness, headaches, sluggishness, and irritability upon waking up if the medication was taken before sleep. This is likely the result of the medication's long half-life, which continues to affect the user after waking up. While benzodiazepines induce sleep, they tend to reduce the quality of sleep by suppressing or disrupting REM sleep. After regular use, rebound insomnia may occur when discontinuing clonazepam. Benzodiazepines may cause or worsen depression.
Sources: en.wikipedia.org
In the 19th and early 20th century, modernist art, politics, science, and culture have come to dominate not only Western Europe and North America, but almost every area on the globe, including movements thought of as opposed to the western world and globalization. The modern era is closely associated with the development of individualism, capitalism, socialism, urbanization and a belief in the positive possibilities of technological and political progress. The brutal wars and other conflicts of this era, many of which come from the effects of rapid change, and the connected loss of strength of traditional religious and ethical norms, have led to many reactions against modern development. Optimism and the belief in constant progress have been most recently criticized by postmodernism, while the dominance of Western Europe and North America over the rest of the world has been criticized by postcolonial theory.
=== Therapeutics === The small size and stability profile of Affimers combined with their human origin confer drug-like properties. This may represent advantages over antibodies in terms of tissue penetration, for example in solid tumours where Avacta are developing PD-L1 inhibitors as alternatives to Opdivo and Yervoy, though requires half life modification to prevent rapid excretion through the kidney. Affimers can be conjugated to form multimers for the design of therapeutics. Examples include the production of multi-specific Affimer molecules to albumin binders to increase their half-life in vivo and for use as the targeting moiety in chimeric receptors or modified to carry a toxin in Affimer-drug conjugates. Affimers as therapeutics are in discovery and preclinical development to tackle cancer, both via CAR-T cell therapy and as checkpoint inhibitors. Early studies using ex vivo human samples showed low immunogenicity associated with the Affimer scaffold, at levels comparable to a marketed antibody therapeutic. Furthermore, initial preclinical studies showed good efficacy and tolerability of the anti-PDL1 immuno-oncology Affimers in mice. It is anticipated that IND filing for the first Affimer therapeutic will occur in 2023.
=== Receptors for water-soluble hormones === Water-soluble hormones include glycoproteins, catecholamines, and peptide hormones composed of polypeptides, e.g. thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone and insulin. These molecules are not lipid-soluble and therefore cannot diffuse through cell membranes. Consequently, receptors for peptide hormones are located on the plasma membrane because they have bound to a receptor protein located on the plasma membrane. Water-soluble hormones come from amino acids and are located and stored in endocrine cells until actually needed. The main two types of transmembrane receptor hormone receptor are the G-protein-coupled receptors and the enzyme-linked receptors. These receptors generally function via intracellular second messengers, including cyclic AMP (cAMP), cyclic GMP (cGMP), inositol 1,4,5-trisphosphate (IP3) and the calcium (Ca2+)-calmodulin system.
Sources: en.wikipedia.org
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.
The fatty diacid chain associates strongly with serum albumin, which keeps the peptide in circulation and shields it from rapid renal clearance. Bound peptide is released gradually, producing a sustained receptor signal. This mechanism also reduces the peak-to-trough variation seen with shorter-acting analogues.
The balance between peripheral receptor activation and signalling in the central nervous system is not fully resolved. The extent to which slowed gastric emptying accounts for reduced energy intake, compared with direct effects on appetite circuits, is debated. Long-term effects on lean mass and on tissues outside the gut and brain are still under study.
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.