A practical reference on deamidation: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-09-24. Anything still debated is marked as such rather than presented as settled.
The peptide activates two G protein-coupled receptors, GIPR and GLP-1R. Binding triggers adenylyl cyclase activity and raises intracellular cyclic AMP in pancreatic beta cells, which potentiates insulin release when glucose is elevated. Signaling in the central nervous system is associated with reduced appetite and lower energy intake, while effects on gastric emptying and glucagon secretion are also reported. Because activity at both receptors is retained, the pharmacological profile is often described as incretin-based rather than selective for a single receptor.
After subcutaneous injection, absorption is gradual, and peak plasma levels are generally reached within one to three days. Albumin binding extends the apparent half-life to roughly five days, which supports a weekly administration schedule. Metabolism proceeds mainly through proteolytic cleavage of the peptide backbone and beta-oxidation of the fatty acid chain, rather than through cytochrome P450 pathways. Eliminated fragments are largely recycled through general protein turnover, and excretion of intact drug in urine is minimal. These properties distinguish the molecule from short-acting incretin mimetics.
Tirzepatide is a synthetic peptide of 39 amino acids engineered from the native glucose-dependent insulinotropic polypeptide sequence. Its structure incorporates several non-natural residues and a C-terminal segment derived from glucagon-like peptide-1, together with a C20 fatty diacid moiety attached through a linker. The lipophilic side chain promotes binding to serum albumin, which slows renal clearance after administration. The compound is classified as a dual incretin receptor agonist and is supplied as a lyophilized powder for reconstitution or as a preformulated solution, depending on the presentation.
Tirzepatide 是一种由 39 个氨基酸组成的合成肽，分子结构上以 GIP 序列为骨架并引入脂肪酸侧链修饰，使其能够同时与葡萄糖依赖性促胰岛素多肽（GIP）受体和胰高血糖素样肽-1（GLP-1）受体结合。这种双重激动特性使它在同类肽类药物中区别于选择性 GLP-1 受体激动剂。该分子最早由一家制药公司在 2010 年代报道，随后进入糖尿病与体重管理领域的临床研究。
在生理层面，GIP 与 GLP-1 均为肠道内分泌细胞分泌的肠促胰素，进食后参与胰岛素分泌调节与胃排空抑制。Tirzepatide 通过同时激活这两条信号通路，使胰岛素分泌的葡萄糖依赖性增强，并延缓冲胃排空、降低食欲信号。与单一 GLP-1 激动相比，双靶点作用在血糖控制和体重变化上的效应幅度更大，但具体贡献比例仍在研究之中。
脂肪酸侧链的存在使该肽与血浆白蛋白结合能力增强，从而延长循环半衰期，支持每周一次给药的用药间隔。白蛋白结合同时改变组织分布特征，减慢肾脏清除速度。该设计思路在多种长效肽类药物中被反复采用，属于既定的药代动力学策略。
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C225H348N48O68 | Approximate composition of the free peptide |
| Molecular weight | Approximately 4813 Da | Calculated for the free base |
| Structural class | Synthetic linear peptide | 39 residues with modified backbone |
| Solubility | Soluble in water and polar solvents | Behavior of the lyophilized solid |
| Typical storage temperature | -20 degrees Celsius or below | Solid form, protected from light |
The GIP receptor is expressed in pancreatic islets, adipose tissue, and the central nervous system, while GLP-1 receptors are found in pancreatic islets, the gastrointestinal tract, and the brain. Activation of both receptors can enhance glucose-dependent insulin secretion and reduce glucagon release. The relative contribution of each receptor to the overall pharmacological effect remains an area of ongoing investigation. Preclinical studies suggest that GIP receptor agonism may modulate appetite and energy balance, but the precise mechanisms in humans are not fully established.
In clinical research, tirzepatide has been studied in randomized controlled trials for glycemic control and body weight reduction. These trials typically measure changes in hemoglobin A1c and body weight over periods of several months. The drug is administered by subcutaneous injection, and its pharmacokinetic profile supports once-weekly dosing. Post-marketing surveillance continues to evaluate long-term outcomes and rare adverse events.
Tirzepatide is a synthetic peptide that acts as a dual agonist at the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors. The molecule contains 39 amino acids and features a C20 fatty diacid moiety attached via a linker, which promotes albumin binding and extends its circulating half-life. Its sequence incorporates non-natural amino acids and modifications that reduce susceptibility to degradation by dipeptidyl peptidase-4. This dual receptor activity distinguishes it from selective GLP-1 receptor agonists.
Lyophilized material is generally held at -20 degrees Celsius or lower, desiccated and protected from light, where it remains stable for extended periods. Reconstituted or ready-to-use solution is usually kept at 2 to 8 degrees Celsius with minimal agitation. Repeated freeze-thaw cycles should be avoided because they promote aggregation and reduce the soluble monomer fraction. Shipment of frozen solid commonly uses dry ice, while refrigerated liquid moves with validated cold packs. Stability beyond documented periods is not established.
Characterization of the peptide relies on reversed-phase high-performance liquid chromatography for purity and related-substance profiling, with ultraviolet detection near 214 nanometers. Mass spectrometry confirms molecular mass and reveals modifications such as oxidation or deamidation. Peptide mapping after enzymatic digestion verifies the amino acid sequence, while amino acid analysis supplies compositional data. Circular dichroism and infrared spectroscopy are used to assess secondary structure, particularly the alpha-helical content that influences aggregation behavior in solution.
Common degradation routes include hydrolysis of labile amide bonds, deamidation of asparagine and glutamine residues, oxidation of methionine and tryptophan, and non-covalent aggregation. Aggregates can form during freeze-thaw cycling, at elevated pH, or when peptide concentration is high. Each route produces characteristic chromatographic or mass shifts that are tracked during stability studies. Whether a given minor impurity alters biological activity is often an open question, and specification limits are typically set on identity and purity rather than on functional data for trace species.
纯度评估通常综合反相色谱、体积排阻色谱与质谱三方面信息：前者反映疏水性杂质，后者反映聚集体，质谱则确认分子量与主要降解产物。有关降解途径的完整图谱——例如脱酰胺、氧化与水解各占多大比例——在不同储存条件下仍有差异，属于需要逐案验证的问题。
质量控制环节关注外观、含量、纯度、有关物质、水分与微生物限度等项目。检测结果需要有对照品和系统适用性数据支持，单次测定不足以判定批次的稳定性。实验室之间方法转移时，色谱柱品牌与梯度差异常导致保留时间漂移，因此方法验证十分必要。
=== Electrochemical sensing === Magneto-electrochemical assays are based on the use of magnetic nanoparticles in electrochemical sensing either by being distributed through a sample where they can collect and preconcentrate the analyte and handled by a magnetic field or by modifying an electrode surface enhancing its conductivity and the affinity with the analyte. Coated-magnetic nanoparticles have a key aspect in electrochemical sensing not only because it facilitates the collecting of analyte but also it allows MNPs to be part of the sensor transduction mechanism. For the manipulation of MNPs in electrochemical sensing has been used magnetic electrode shafts or disposable screen-printed electrodes integrating permanent bonded magnets, aiming to replace magnetic supports or any external magnetic field.
==== Distribution ==== Gabapentin, pregabalin, Baclofen and phenibut all cross the blood–brain barrier and enter the central nervous system. However, due to their low lipophilicity, the gabapentinoids require active transport across the blood–brain barrier. The LAT1 is highly expressed at the blood–brain barrier and transports the gabapentinoids that bind to it across into the brain. As with intestinal absorption of gabapentin mediated by LAT1, transport of gabapentin across the blood–brain barrier by LAT1 is saturable. Gabapentin does not bind to other drug transporters such as P-glycoprotein (ABCB1) or OCTN2 (SLC22A5). Gabapentin and pregabalin are not significantly bound to plasma proteins (<1%). Baclofen shows low plasma protein binding of 30%.
=== Paleomagnetic dating === A sequence of paleomagnetic poles (usually called virtual geomagnetic poles), which are already well defined in age, constitutes an apparent polar wander path (APWP). Such a path is constructed for a large continental block. APWPs for different continents can be used as a reference for newly obtained poles for the rocks with unknown age. For paleomagnetic dating, it is suggested to use the APWP in order to date a pole obtained from rocks or sediments of unknown age by linking the paleopole to the nearest point on the APWP. Two methods of paleomagnetic dating have been suggested: (1) the angular method and (2) the rotation method. The first method is used for paleomagnetic dating of rocks inside of the same continental block. The second method is used for the folded areas where tectonic rotations are possible.
Sources: en.wikipedia.org
Southern Kuriles / Northern Territories: A Stumbling-block in Russia-Japan Relationship, history and analysis by Andrew Andersen, Department of Political Science, University of Victoria, May 2001 http://depts.washington.edu/ikip/index.shtml (Kuril Island Biocomplexity Project) Kuril Islands at Ocean Dots.com at the Wayback Machine (archived 23 December 2010) (includes space imagery) Kuril Islands at Natural Heritage Protection Fund The International Kuril Island Project http://www.mofa.go.jp/region/europe/russia/territory/index.html Chishima: Frontiers of San Francisco Treaty in Hokkaido Short film on the disputed islands from a Japanese perspective USGS Map showing location of Magnitude 8.3 Earthquake 46.616°N, 153.224°E Kuril Islands region, November 15, 2006 11:14:16 UTC Pictures of Cats – Kurilian Bobtail Pictures of Kuril Islands Kuril Islands at Encyclopædia Britannica
In molecular biology, the BtpA protein family is a family of proteins which includes BtpA. BtpA appears to play a role in the stabilisation of photosystem I. It is an extrinsic membrane protein located on the cytoplasmic side of the thylakoid membrane. Homologs of BtpA are found in the Thermoproteota and "Euryarchaeota", where their function remains unknown. The Ycf4 protein is firmly associated with the thylakoid membrane, presumably through a transmembrane domain. Ycf4 co-fractionates with a protein complex larger than PSI upon sucrose density gradient centrifugation of solubilised thylakoids. The Ycf3 protein is loosely associated with the thylakoid membrane and can be released from the membrane with sodium carbonate. This suggests that Ycf3 is not part of a stable complex and that it probably interacts transiently with its partners. Ycf3 contains a number of tetratricopeptide repeats (TPR); TPR is a structural motif present in a wide range of proteins, which mediates protein-protein interactions.
Naturally occurring rhenium (75Re) is 37.4% 185Re, which is stable (although it is predicted to decay), and 62.6% 187Re, which is unstable but has a very long half-life (4.16×1010 years). Among elements with a known stable isotope, only indium and tellurium similarly occur with a stable isotope in lower abundance than the long-lived radioactive isotope. There are 36 other unstable isotopes recognized, the longest-lived of which are 183Re with a half-life of 70 days, 184Re with a half-life of 35.4 days, 186Re with a half-life of 3.7185 days, 182Re with a half-life of 64.2 hours, and 189Re with a half-life of 24.3 hours. There are also numerous isomers, the longest-lived of which are 186mRe with a half-life of 200,000 years and 184mRe with a half-life of 177.25 days. All others have half-lives less than a day.
In some cases, withdrawal symptoms may be prevented by taking medication as directed, and when discontinuing, doing so gradually, although symptoms may appear while tapering. When discontinuing an antidepressant with a short half-life, switching to a drug with a longer half-life (e.g., fluoxetine or citalopram) and then tapering, and eventually discontinuing, from that drug can decrease the severity of symptoms in some cases. Gradual tapering over weeks to months is commonly recommended to reduce withdrawal symptoms, although direct comparative evidence on optimal taper duration is limited. A NICE committee noted that variability in withdrawal symptoms and tapering response among patients prevented the recommendation of a specific tapering timeline, and that an individualized approach to tapering is warranted. Treatment is dependent on the severity of the discontinuation reaction and whether or not further antidepressant treatment is warranted. In cases where further antidepressant treatment is prescribed, then the only option suggested may be restarting the antidepressant. If antidepressants are no longer required, treatment depends on symptom severity. If symptoms of discontinuation are severe, or do not respond to symptom management, the antidepressant can be reinstated and then withdrawn more cautiously, or by switching to a drug with a longer half-life (e.g., fluoxetine), and then tapering and discontinuing that drug. In severe cases, hospitalization may be required.
Sources: en.wikipedia.org
To claim this reward, a special transaction called a coinbase is included in the block, with the miner as the payee. All bitcoins in existence have been created through this type of transaction. This reward is halved every 210,000 blocks until ₿21 million have been issued in total, which is expected to occur around the year 2140. Afterward, miners will only earn from transaction fees. These fees are determined by the transaction's size and the amount of data stored, measured in satoshis per byte. The proof of work system and the chaining of blocks make blockchain modifications very difficult, as altering one block requires changing all subsequent blocks. As more blocks are added, modifying older blocks becomes increasingly challenging. In case of disagreement, nodes trust the longest chain, which required the greatest amount of effort to produce. To tamper or censor the ledger, one needs to control the majority of the global hashrate. The high cost required to reach this level of computational power secures the bitcoin blockchain. The environmental impact of bitcoin mining is controversial and has attracted the attention of regulators, leading to restrictions or incentives in various jurisdictions. As of 2025, a non-peer-reviewed study by the Cambridge Centre for Alternative Finance (CCAF) estimated that bitcoin mining represented 0.5% of global electricity consumption and 0.08% of world greenhouse gas emissions, comparable to Slovakia's emissions. About half of the electricity used is generated through fossil fuels.
Major Crispin Nicholas Black (511814), Welsh Guards. Major Alexander Thomas Boyd (496287), The Royal Logistic Corps. Major Joseph Bright (518051), Adjutant General's Corps (SPS). 24652448 Sergeant (Acting Staff Sergeant) David William Brown, The Royal Logistic Corps. Major Malcolm Hugh Peter Buchanan (495490), The Royal Logistic Corps. 24330851 Warrant Officer Class 1 Andrew Kenneth George Card, The Royal Logistic Corps. Major Steven Cheetham, , (495676), Corps of Royal Engineers (Volunteers), Territorial Army. Acting Lieutenant Colonel John Cobb (448934), Stonyhurst College Combined Cadet Force, Territorial Army. Major Gavin Terence Collinson (501572), The Royal Logistic Corps. 24563002 Staff Sergeant Anthony Raymond Cooper, Adjutant General's Corps (RMP). 24185755 Warrant Officer Class 1 Alan John Crawford, Scots Guards. 24198806 Warrant Officer Class 1 William Crook, Adjutant General's Corps (SPS). 23962020 Staff Sergeant Graham Stuart Daniell, Corps of Royal Electrical and Mechanical Engineers. 24511850 Sergeant (Acting Colour Sergeant) Stephen Denham, The Worcestershire and Sherwood Foresters Regiment. 24072935 Staff Sergeant John James Flannigan, The Light Dragoons. Captain John William Alexander France, , (508406), The Green Howards (Volunteers), Territorial Army. 24750683 Corporal Michael Sean Gill, Corps of Royal Engineers. Major Richard Duncan Brownrigg Gordon (513813), Adjutant General's Corps (ETS). Major Paul Anthony Philip Griffiths (517124) Royal Regiment of Artillery. Captain (Queen's Gurkha Officer) Dharmendra Gurung (537028), The Royal Gurkha Rifles.
Figuratively translated as "Persevering through Hardship (for the sake of revenge)", the saying is derived from the Chinese chengyu of wòxīnchángdǎn (臥薪嘗膽), literally meaning "sleeping on sticks and tasting gall", that alludes to the perseverance of King Goujian of Yue (reigned 496–465 BC) in the war between Wu and Yue. For modern Japan, this ideology meant an increase in heavy industry and the strength of the armed forces, especially the navy, at the expense of individual wants and needs. The Triple Intervention had a profound effect on Japanese foreign relations, as Japanese diplomacy sought to avoid a reconstitution of a combination of European powers against Japan. It led directly to the Anglo-Japanese Alliance of 1902 which was explicitly intended to shield Japan from interference from other European great powers, and from Russia in particular.
In April 1918, after the German-Russian Treaty of Brest-Litovsk, Austrian Foreign Minister Count Ottokar Czernin made a speech attacking incoming French Prime Minister Georges Clemenceau as being the main obstacle to a peace favouring the Central Powers. Clemenceau was incensed and, after seeing Emperor Charles's letter of 24 March 1917, had it published. For a while, the life of Sixtus appeared to be in danger, and there were even fears that Germany might occupy Austria. Czernin persuaded Charles to send a 'Word of Honour' to Austria's allies saying that Sixtus had not been authorised to show the letter to the French Government, that Belgium had not been mentioned, and that Clemenceau had lied about the mention of Alsace. Czernin had actually been in contact with the German Embassy throughout the whole crisis and attempted to persuade the Emperor to step down because of the Affair. After failing to do so, Czernin resigned as Foreign Minister.
Females become receptive to courting males about 8–12 hours after emergence. Specific neuron groups in females have been found to affect copulation behavior and mate choice. One such group in the abdominal nerve cord allows the female fly to pause her body movements to copulate. Activation of these neurons induces the female to cease movement and orient herself towards the male to allow for mounting. If the group is inactivated, the female remains in motion and does not copulate. Various chemical signals such as male pheromones often are able to activate the group. Also, females exhibit mate choice copying. When virgin females are shown other females copulating with a certain type of male, they tend to copulate more with this type of male afterwards than naïve females (which have not observed the copulation of others). This behavior is sensitive to environmental conditions, and females copulate less in bad weather conditions.
Sources: en.wikipedia.org
It is a synthetic linear peptide that acts as a dual agonist at the GIP and GLP-1 receptors. It combines a modified incretin backbone with a fatty diacid side chain that extends its circulation time. It is not a small-molecule drug and is not orally absorbed in its native form.
Single-receptor agents act predominantly at GLP-1R. Tirzepatide retains activity at GIPR, which is expressed in pancreatic islets, adipose tissue, and the central nervous system. The contribution of each receptor to the overall response is still an area of active study, and the relative weight of GIPR signaling in humans is not fully settled.
The fatty diacid moiety binds serum albumin, which reduces renal filtration of the active peptide. Additional resistance to enzymatic breakdown comes from non-natural residues in the backbone. Together these features produce an apparent half-life of about five days and permit weekly dosing intervals.
它属于合成修饰肽，同时激动 GIP 与 GLP-1 两种肠促胰素受体。这类分子通常被称为双重肠促胰素受体激动剂，与选择性 GLP-1 激动剂在靶点范围上不同。