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.
Last reviewed on 2025-12-10. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
The distinction between established facts and open questions matters here. That the peptide binds the GLP-1 receptor and stimulates insulin release in a glucose-dependent manner is well documented. How individual variability in receptor density, gastric emptying rate, and gut microbiome composition shapes response remains an active research area. Long-term outcomes beyond five years of continuous use are not yet fully characterized in published trials, and several extension studies are ongoing.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1, a hormone released from intestinal L cells after food intake. The molecule is a 31-amino-acid backbone modified at three positions to resist cleavage by dipeptidyl peptidase-4, the enzyme that degrades native GLP-1 within minutes. A lysine residue at position 26 carries a linker and a C18 fatty diacid, which promotes binding to serum albumin and slows renal clearance. These changes extend the circulating half-life from roughly two minutes to about one week in humans.
| 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.
序列层面的改动同时解决了两个问题，即酶解稳定性与肾脏清除速度。天然 GLP-1 在循环中的半衰期仅约两分钟，主要被二肽基肽酶-4 迅速灭活。酰化侧链与白蛋白的可逆结合形成循环储库，使分子缓慢释放并持续激活受体。这种设计思路后来被广泛用于同类长效肽的开发，属于该类药物化学改造的典型范式。
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。
Tissues which take up stains are called chromatic. Chromosomes were so named because of their ability to absorb a violet stain. Positive affinity for a specific stain may be designated by the suffix -philic. For example, tissues that stain with an azure stain may be referred to as azurophilic. This may also be used for more generalized staining properties, such as acidophilic for tissues that stain by acidic stains (most notably eosin), basophilic when staining in basic dyes, and amphophilic when staining with either acid or basic dyes. In contrast, chromophobic tissues do not take up coloured dye readily.
==== Interleukin-6 (IL-6) ==== IL-6 is thought to cause muscle loss by starting a pathway called the JAK/STAT pathway. IL-6 is produced by immune cells called macrophages, potentially producing acute phase reactants which may worsen muscle loss. Other molecules may include:
The first wave of modern Jewish migration to Ottoman-ruled Palestine, known as the First Aliyah, began in 1881, as Jews fled pogroms in Eastern Europe. Although the Zionist movement already existed in practice, Austro-Hungarian journalist Theodor Herzl is credited with founding political Zionism, a movement that sought to establish a Jewish state in Palestine, thus offering a solution to the so-called Jewish question of the European states, in conformity with the goals and achievements of other national projects of the time. In 1896, Theodor Herzl set out his vision of a Jewish state and homeland for the Jewish people in his book Der Judenstaat (The Jewish State). The following year he presided over the First Zionist Congress in Basel, at which the Zionist Organization was founded. The draft of the objective of the modern Zionist movement submitted to the First Zionist Congress of the Zionist Organization in 1897 read: "Zionism seeks to establish a home for the Jewish people in Palestine secured by law." One delegate sought to replace "by law" with "by international law", which was opposed by others. A compromise formula was adopted, which came to be known as the Basel Program, and read:
== Medical Applications/Pharmacology == Hyperglycemia, a side effect caused by diabetes, combines with oxidative stress to create advanced glycation end-products (AGEs) that can lead to diabetic retinopathy (DR), age related macular degeneration (AMD) and cataracts. Enhancing the glyoxalase system has been shown to delay accumulation of AGEs and associated retinal damage in animals that consume higher glycemic index diets. This was corroborated upon over-expression of GLO1, which in C. elegans reduced basal MG concentration, prevented mitochondrial protein modification and enhanced lifespan. Similarly, in mice, GLO1 over-expression reduced baseline MG concentrations in the brain. In diabetic mice, it prevented diabetes-induced increases in MG modification of glomerular proteins, reduced oxidative stress, and prevented development of diabetic kidney pathology, despite unchanged levels of hyperglycemia. Western diets, typically high in glycemic index, exacerbate AGE accumulation and amplify aging-related damage. Enhancing the glyoxalase system may offer a promising therapeutic strategy to prevent the onset and progression of AGEs-related diseases. Oxidative stress can lead to worsening neurological diseases such as Alzheimer's, Parkinson's, and Autism Spectrum Disorder. Flavonoids, a type of antioxidant that combats oxidative stress in the body, has been found to help decrease the production of radical oxygen species (ROS) mostly by preventing the formation of free radicals, additionally they partially enhance the transcription of glyoxalase.
Sources: en.wikipedia.org
The Newcomb Cleveland Prize of the American Association for the Advancement of Science (AAAS) is annually awarded to author(s) of outstanding scientific paper published in the Research Articles or Reports sections of Science. Established in 1923, funded by Newcomb Cleveland who remained anonymous until his death in 1951, and for this period it was known as the AAAS Thousand Dollar Prize. "The prize was inspired by Mr. Cleveland's belief that it was the scientist who counted and who needed the encouragement an unexpected monetary award could give." The present rules were instituted in 1975, previously it had gone to the author(s) of noteworthy papers, representing an outstanding contribution to science, presented in a regular session, sectional or societal, during the AAAS Annual Meeting. It is now sponsored by the Fodor Family Trust and includes a prize of $25,000. The prize's current sponsorship has a notable connection to a past winner: Stephen P. A. Fodor, founder of Affymetrix, received the prize in 1990 for a paper introducing microarray technology. Affymetrix added its support to the prize in 2003, more than doubling its monetary value at the time. Winners receive a bronze medal, a share of the prize money, and reimbursement for travel to the AAAS Annual Meeting. Final selection is determined by a panel of distinguished scientists appointed by the editor-in-chief of Science. The annual contest period runs from the first issue of June through the last issue of the following May. No prize was awarded in 1942–1945, 1948, 1973, 1975, or 1976.
This is a big step up from previous methods which could only predict based on a single domain pair. The limitation of this method is that it relies on the training dataset to produce results. Thus, usage of different training datasets could influence the results. A caveat of most methods is the lacks negative data, e.g non-interactions for proteins which can be overcome using topology-driven negative sampling.
== Literature == Carl-Gerd Dieris: Zur Frage der Luminiszenz von thermooxidativ geschädigten Polycarpolaktam. Eine neue Synthese des Bakterienfarbstoffes Indigoidin und seiner Tetra-N-alkylderivate. 1980. Hans Günter Schlegel: Allgemeine Mikrobiologie. Thieme Verlagsgruppe, Stuttgart 1992, ISBN 978-3-13-444607-4. Reverchon, Sylvie; Rouanet, Carine; Expert, Dominique; Nasser, William (2002-01-02). "Characterization of Indigoidine Biosynthetic Genes in Erwinia chrysanthemi and Role of This Blue Pigment in Pathogenicity". Journal of Bacteriology. 184 (3): 654–665. doi:10.1128/JB.184.3.654-665.2002. PMC 139515. PMID 11790734. Christin Schönfeld: Charakterisierung und biochemische Analyse der Indigoidin Synthease BpsA aus S. lavendulae ATCC 11924. Masterarbeit, Philipps-Universität Marburg 2012. M. Müller, S. Ausländer, D. Ausländer, C. Kemmer, M. Fussenegger: A novel reporter system for bacterial and mammalian cells based on the non-ribosomal peptide indigoidine. Metabolic Engineering 14/2012, S. 325–335 (doi:10.1016/j.ymben.2012.04.002). H. Kobayashi, Y. Nogi, K. Hirokoshi: New violet 3,3'-bipyridyl pigment purified from deep-sea microorganism Shewanella violacea DSS12. In: Extremophiles Nr. 11(2)/2012, S. 245–250. PMID 17102923.
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.
It is a modified version of the natural hormone, with three amino acid changes and a fatty acid side chain added. These edits extend its half-life from minutes to about one week. The core receptor activity is retained.