deamidation 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.
Updated 2025-11-06. Numbers and descriptions here follow the published literature rather than marketing material.
The primary target is the GLP-1 receptor, a class B G protein-coupled receptor expressed on pancreatic beta cells, in the gut, and in several brain regions. Receptor activation raises intracellular cyclic AMP, which potentiates glucose-dependent insulin secretion and lowers glucagon release when blood glucose is elevated. Signalling in the hypothalamus and brainstem is associated with reduced appetite and slower gastric emptying. Because the insulinotropic effect depends on prevailing glucose levels, the hypoglycaemic risk of the peptide alone is described as low in most study settings. The relative contribution of peripheral and central actions remains an active research question.
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.
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.
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.
| 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 |
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.
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.
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.
=== Lanthipeptides === Lanthipeptides are one of the most well-studied families of RiPPs. The family is characterized by the presence of lanthionine (Lan) and 3-methyllanthionine (MeLan) residues in the final natural product. There are four major classes of lanthipeptides, delineated by the enzymes responsible for installation of Lan and MeLan. The dehydratase and cyclase can be two separate proteins or one multifunctional enzyme. Previously, lanthipeptides were known as "lantipeptides" before a consensus was reached in the field. Lantibiotics are lanthipeptides that have known antimicrobial activity. The founding member of the lanthipeptide family, nisin, is a lantibiotic that has been used to prevent the growth of food-born pathogens for over 40 years.
=== Pharmacodynamics === (+)-Desmetramadol is a G-protein biased μ-opioid receptor full agonist. It shows comparatively far lower affinity for the δ- and κ-opioid receptors. The two enantiomers of desmetramadol show quite distinct pharmacological profiles; both (+) and (−)-desmetramadol are inactive as serotonin reuptake inhibitors, but (−)-desmetramadol retains activity as a norepinephrine reuptake inhibitor, and so the mix of both the parent compound and metabolites contributes significantly to the complex pharmacological profile of tramadol. While the multiple receptor targets can be beneficial in the treatment of pain (especially complex pain syndromes such as neuropathic pain), they increase the potential for drug interactions compared to other opioids, and may also contribute to side effects. Desmetramadol is also an antagonist of the serotonin 5-HT2C receptor, at pharmacologically relevant concentrations, via competitive inhibition. This suggests that the apparent anti-depressant properties of tramadol may be at least partially mediated by desmetramadol, thus prolonging the duration of therapeutic benefit. Inhibition of the 5-HT2C receptor is a suggested factor in the mechanism of anti-depressant effects of agomelatine and maprotiline. The potential selectivity and favorable side effect profile of desmetramadol compared to tramadol, makes it more suitable for use as antidepressant, although clinical development appears to have stopped.
== External links == Clinical trial number NCT00372593 for "Combination Chemotherapy With or Without Gemtuzumab in Treating Young Patients With Newly Diagnosed Acute Myeloid Leukemia" at ClinicalTrials.gov
Sources: en.wikipedia.org
Tim Hortons franchises spread rapidly and eventually overtook McDonald's as Canada's largest food service operator. The company opened twice as many Canadian outlets as McDonald's by 2005, and system-wide sales also surpassed those of McDonald's Canadian operations as of 2002. The chain accounted for 22.6% of all fast-food industry revenues in Canada in 2005. Under pressure from major investors Peter May and Nelson Peltz, in late 2005, Wendy's announced it would sell between 15% and 18% of the Tim Hortons operations in an initial public offering, which was completed on March 24, 2006, and subsequently said it would spin-off to shareholders its remaining interest by the end of 2006. Wendy's cited increased competition between the two chains and Tim Hortons' increasing self-sufficiency as reasons for its decision, but the company had been under shareholder pressure to make such a move because of the strength and profitability of the Tim Hortons brand. Shares of the company began trading on March 24, 2006, with an initial public offering of CA$27 per share, raising over $700 million in the first day of trading. On September 24, Wendy's spun off the rest of its shares in Tim Hortons by distributing the remaining 82% to its shareholders. On the same day, Tim Hortons was added to Canada's benchmark stock-market indicator, the S&P/TSX Composite Index, and to the S&P/TSX 60.
On January 24, 2025, less than a week into Trump's second presidency, he fired 17 independent inspectors general at federal agencies, which appeared to violate federal law that requires advance notice of dismissals to both chambers of congress with reasons given 30 days in advance. Trump also fired all Democratic but not Republican members of the Privacy and Civil Liberties Oversight Board, which would prevent the board from meeting quorum and functioning. Trump also fired members of the Equal Employment Opportunity Commission, National Labor Relations Board and 56 senior officials at USAID for allegedly attempting to thwart his priorities.
The company set up a ghostwriting programme called CASPPER, initially to produce articles about Paxil but which was extended to cover Avandia. As part of the settlement GSK signed a five-year corporate integrity agreement with the Department of Health and Human Services, which obliged the company to make major changes in the way it did business, including changing its compensation programmes for its sales force and executives, and to implement and maintain transparency in its research practices and publication policies. It announced in 2013, that it would no longer pay doctors to promote its drugs or attend medical conferences, and that its sales staff would no longer have prescription targets.
=== Ron Hites Award: for an exemplary paper published in the previous two volumes of the Journal of the American Society for Mass Spectrometry (since 2009) === 2022 Elyssia Gallagher 2019 Julia Laskin 2009 Alison Ashcroft
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 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.