The short version of circular dichroism fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-12-01 and is reviewed periodically as new material appears.
Tirzepatide is a synthetic peptide built from thirty-nine amino acids. Its sequence is derived from native glucose-dependent insulinotropic polypeptide, or GIP, with several non-natural residues and a fatty diacid side chain attached through a linker. The molecule behaves as a dual agonist at two incretin receptors, GIP and GLP-1, instead of targeting a single receptor. This dual engagement separates it from earlier single-receptor incretin compounds and underpins most of its reported pharmacological activity.
At the receptor level, the compound binds both GIP and GLP-1 receptors and triggers downstream signalling that raises cyclic AMP in target cells. GLP-1 receptor activation is associated with glucose-dependent insulin release, slower gastric emptying, and reduced appetite signalling. GIP receptor activation contributes effects that are less completely characterised, and how much each receptor adds to the overall clinical response is still an open question. The two pathways appear to interact in a complementary rather than a purely additive way.
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。
该化合物的名称与结构由国际非专利名称体系统一维持，不同文献中出现的同义写法主要在拼写顺序或盐形式描述上不同。研究者通常通过受体结合实验、细胞内环磷酸腺苷积累测定以及动物模型来确认其双激动活性。相当一部分分子层面的细节——例如两条受体通路之间的信号交叉作用——尚处于开放问题状态。
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C225H348N48O68 | Free base form |
| Molecular mass | Approximately 4813 Da | Calculated from the sequence |
| Amino acid residues | 39 | GIP-derived backbone |
| Receptor targets | GIP and GLP-1 | Dual agonist |
| Circulating half-life | About 5 days | Supports weekly administration |
Development of tirzepatide took place under a research program that sought to test whether simultaneous engagement of two incretin receptors would produce greater metabolic effects than single-receptor agonism. Clinical trials were organized into the SURPASS series for type 2 diabetes and the SURMOUNT series for obesity and weight management. Regulatory clearance for type 2 diabetes came in 2022 in the United States, followed by approval for chronic weight management in 2023. The trial programs reported reductions in glycated hemoglobin and body weight relative to comparators, though long-term cardiovascular and durability data continue to accumulate.
The peptide backbone contains 39 amino acids and includes alpha-aminoisobutyric acid residues, which are not among the standard proteinogenic set. A C20 fatty diacid moiety is attached through a linker, allowing the compound to bind serum albumin and extend its circulation time. This albumin binding is the main reason the molecule supports once-weekly administration rather than more frequent dosing. The measured molecular mass is approximately 4,813 daltons, placing it firmly in the peptide rather than small-molecule class.
Solid tirzepatide is handled as a lyophilised, hygroscopic peptide powder that should be kept desiccated, protected from light, and stored frozen, typically at or below minus twenty degrees Celsius for long-term retention. Material left at ambient temperature for extended periods can take up moisture, which promotes aggregation and deamidation. Commercial liquid presentations are kept refrigerated between two and eight degrees Celsius and are not frozen. Reconstituted laboratory solutions are generally held cold and used within a short window because hydrolysis and oxidation continue slowly in solution.
Identity and purity are usually established with reversed-phase high-performance liquid chromatography for the main peak and with mass spectrometry for the observed molecular mass. Peptide mapping after enzymatic digestion confirms the primary sequence, while amino acid analysis provides a quantitative composition check. Size-exclusion chromatography and ion-exchange chromatography are used to look for aggregates and charge variants. Water content, residual solvents, and counter-ion content are measured separately, since a lyophilised powder is often reported on an as-is basis unless a correction is applied.
Research-grade material circulates through suppliers that differ widely in documentation and testing practice, so a certificate of analysis is a starting point rather than proof of quality. Independent verification typically repeats chromatographic purity and mass confirmation on the received lot, and compares results against a retained reference standard. Regulatory status varies by jurisdiction, and a substance cleared as a medicine is not interchangeable with a research chemical of the same name. Open questions include how closely non-pharmaceutical lots match approved material in impurity profile and in aggregate content.
Recommended storage for reference material is a freezer at approximately -20 degrees Celsius, protected from light and moisture. Commercial injectable presentations are stored refrigerated between 2 and 8 degrees Celsius and must not be frozen. Product labelling generally permits a limited period at controlled room temperature once dispensed, with the exact window depending on the presentation. Repeated temperature cycling is avoided because it can promote aggregation or deamidation of the peptide chain.
Identity and purity are assessed by reversed-phase high-performance liquid chromatography, with mass confirmation by electrospray ionisation mass spectrometry. Peptide mapping after enzymatic digestion verifies the primary sequence. Size-exclusion chromatography quantifies aggregates, while circular dichroism provides a secondary-structure fingerprint. Bioanalytical quantification in plasma uses immunoassay or LC-MS/MS. Reported purity for research-grade lots is commonly 95 percent or higher, and residual water content is checked by Karl Fischer titration.
As a peptide, tirzepatide is handled as a lyophilised solid in research settings and as a preserved solution in finished products. Aqueous solubility is pH dependent and reaches a minimum near the isoelectric point, which lies close to pH 5.4. Stock solutions are typically prepared in neutral or slightly basic buffer to limit precipitation. The solid is hygroscopic and should be equilibrated to room temperature before opening so that condensation does not form on the powder surface.
Routine characterization of the peptide relies on reversed-phase high-performance liquid chromatography for purity assessment, usually with ultraviolet detection near 214 nanometers. Intact mass measurement by liquid chromatography coupled to mass spectrometry confirms molecular identity against a theoretical value. Sequence-level confirmation uses enzymatic digestion followed by tandem mass spectrometry, an approach known as peptide mapping. Amino acid analysis gives an independent check on composition. Circular dichroism spectra are used to estimate helical content in aqueous buffer.
Stability depends strongly on physical form. The dry powder is generally regarded as stable for extended periods when held at or below minus twenty degrees Celsius in a sealed, desiccated container. In solution, degradation pathways include deamidation of asparagine and glutamine residues, oxidation of methionine, and aggregation. Reaction rates for these pathways rise with temperature. Repeated freezing and thawing of solutions promotes aggregation, and light exposure can accelerate some oxidative changes. Buffer composition and pH influence which pathway dominates at a given temperature.
Regulatory and quality discussions place the peptide within established guidance for synthetic peptides and biologics. Forced degradation studies, in which samples are exposed to heat, acid, base, peroxide, and light, identify likely degradation products and validate the selectivity of analytical methods. Reference standards allow comparison across laboratories and production batches. Purity specifications reported in the literature usually combine chromatographic purity with mass confirmation. Which impurity thresholds are meaningful for long-term behavior is still debated, and no single universal specification has been adopted across all jurisdictions.
=== Legal status === Lorazepam is a Schedule IV drug under the Controlled Substances Act in the US and internationally under the United Nations Convention on Psychotropic Substances. It is a Schedule IV drug under the Controlled Drugs and Substances Act in Canada. In the United Kingdom, it is a Class C, Schedule 4 Controlled Drug under the Misuse of Drugs Regulations 2001.
On December 2, 2009, Akram Elias traveled to the Hotel Nacional de Cuba in Havana to meet with Alan Gross. Gross was arrested the next night, on December 3, 2009, sentenced to 15 years in prison for subversion. Gross and his lawyers maintained that if he had been carrying clandestine intelligence materials into the country, that he was doing it unknowingly. In 2010, the Grand Lodge of Cuba publicly accused former Grand Master Collera Venta and two other Cuban Freemasons of corruption and dereliction of duty. They accused these men of allowing a foreigner, a Freemason from Miami, to attend a meeting at a Temple in Cuba in 2009. They alleged that this violated a rule that only allowed Cuban Freemasons into the Temple. The Supreme Court of Masonic Justice set a trial date for June 2010, and sent out "Masonic investigators" of the Court to determine the facts of the case. Collera Venta wrote a letter in April 2010 in which he said that the accusations were false, and insisted that Cuban exiles were to blame.
=== Canada === In Canada, Canadian medical graduates (CMGs), which includes final-year medical students and unmatched previous-year medical graduates, apply for residency positions via the Canadian Resident Matching Service (CaRMS). The first year of residency training is known as "Postgraduate Year 1" (PGY1). CMGs can apply to many post-graduate medical training programs including family medicine, emergency medicine, internal medicine, pediatrics, general surgery, obstetrics-gynecology, neurology, and psychiatry, amongst others. Some residency programs are direct-entry (family medicine, dermatology, neurology, general surgery, etc.), meaning that CMGs applying to these specialties do so directly from medical school. Other residencies have sub-specialty matches (internal medicine and pediatrics) where residents complete their first 2–3 years before completing a secondary match (Medicine subspecialty match (MSM) or Pediatric subspecialty match (PSM)). After this secondary match has been completed, residents are referred to as fellows. Some areas of subspecialty matches include cardiology, nephrology, gastroenterology, immunology, respirology, infectious diseases, rheumatology, endocrinology and more. Direct-entry specialties also have fellowships, but they are completed at the end of residency (typically 5 years).
Sources: en.wikipedia.org
Umami ( from Japanese: うま味, pronounced [ɯmami]), or savoriness, is one of the five basic tastes. It is characteristic of broths and cooked meats. People taste umami through taste receptors that typically respond to glutamates and nucleotides, which are widely present in meat broths and fermented products. Glutamates are commonly added to some foods in the form of monosodium glutamate (MSG), and nucleotides are commonly added in the form of disodium guanylate, inosine monophosphate (IMP) or guanosine monophosphate (GMP). Since umami has its own receptors rather than arising out of a combination of the traditionally recognized taste receptors, scientists now consider umami to be a distinct taste. Food, beverages, or condiments that have a strong umami flavor include meats, shellfish, fish (including fish sauce and preserved fish such as Maldives fish, katsuobushi, sardines, and anchovies), dashi, tomatoes, mushrooms, hydrolyzed vegetable protein, meat extract (Bouillon cubes), yeast extract (beer, Marmite, Vegemite), kimchi, cheeses (Parmesan, Asiago cheese, or blue cheese), as well as sauces such as A1 sauce, Worcestershire sauce, and soy sauce. In 1908, Kikunae Ikeda of the University of Tokyo scientifically identified umami as a distinct taste attributed to glutamic acid. As a result, in 1909, Ikeda and Saburōsuke Suzuki founded Ajinomoto Co., Inc.
== Diagnosis == The diagnosis of JIA can be difficult, in part because joint pain in children is so common and may be from many causes other than JIA. The characteristic feature of arthritis is joint swelling which is sometimes – but not always – associated with pain. The presence of joint stiffness is another typical feature, particularly when present in the morning and improving with activity. No single test can confirm a diagnosis of JIA: a combination of presenting signs and symptoms, blood tests, and if necessary medical imaging, is used to make the diagnosis. The blood tests may measure levels of inflammatory markers, as well as the presence of specific immune markers which may include anti-nuclear antibody, HLA-B27, rheumatoid factor and anti–citrullinated protein antibody. These serological markers may be negative in children with JIA, and are often present in healthy children; as such they should not be interpreted in isolation but in the context of the clinical presentation. Many children with JIA have normal blood work. X-rays may be required to ensure that the joint pain and swelling is not from a fracture, cancer, infection, or congenital abnormality. In some cases, fluid from the joint can be aspirated and analysed to assist in making a diagnosis. This test can assist by ruling out other causes of arthritis such as infection.
Abdomen and obliques (belly) Crunch (i) Leg raise (c) Russian twist (c) Sit-up (c) Biceps (front of upper arms) Biceps curl (i) Pull ups with a supinated grip Calves Calf raise (i) Deltoids (shoulders) Front raise (i) Head stand into Handstand push-up (c) Lateral raise (i) Military press (c) Rear delt raise (i) Shoulder press (c) Upright row (c) Forearms Wrist curl (i) Wrist extension (i) Hamstrings (back of thighs) Deadlift (c) Frog jumping (i) Good-morning (exercise) (c) Leg curl (i) Squat (c) Lats and trapezius (back) Bent-over row (c) Chin-up (c) Pulldown (c) Pullup (c) Seated row (c) Shoulder shrug (i) Supine row (c) Lower back Deadlift (c) Good-morning (exercise) (c) Hyperextension (c) Pectorals (chest) Bench press (c) Chest fly (i) Dips (c) Machine fly (i) Push-up (c) Pelvis Vaginal weightlifting Quadriceps (front of thighs) Frog Jumping (i) Leg extension (i) Leg press (c) Lunge (c) Squat (c) Triceps (back of upper arms) Close-grip bench press (c) Dips (c) Push-down (exercise) (i) Lying triceps extensions (i)
A synarthrosis is a type of joint which allows no movement under normal conditions. Sutures and gomphoses are both synarthroses. Joints which allow more movement are called amphiarthroses or diarthroses. Syndesmoses are considered to be amphiarthrotic, because they allow a small amount of movement.
Sources: en.wikipedia.org
Canada-wide in 2014, they were technically illegal to sell, as no nicotine-containing e-cigarettes are not regulated by Health Canada, but this is generally unenforced and they are commonly available for sale Canada-wide. In 2016, Health Canada announced plans to regulate vaping products. In the US and the UK, the use and sale to adults of e-cigarettes are legal. The revised EU Tobacco Products Directive came into effect in May 2016, providing stricter regulations for e-cigarettes. It limits e-cigarette advertising in print, on television and radio, along with reducing the level of nicotine in liquids and reducing the flavors used. It does not ban vaping in public places. It requires the purchaser for e-cigarettes to be at least 18 and does not permit buying them for anyone less than 18 years of age. The updated Tobacco Products Directive has been disputed by tobacco lobbyists whose businesses could be impacted by these revisions. The US FDA regulates e-cigarettes, e-liquid and all related products. It evaluates ingredients, product features and health risks, as well their appeal to minors and non-users. The FDA rule also bans access to minors. A photo ID is now required to buy e-cigarettes, and their sale in all-ages vending machines is not permitted in the US.
== Significance == The Islamabad Talks represented the first instance of direct high-level, in-person engagement between the United States and Iran since the 1979 Islamic revolution. They were widely regarded as a critical diplomatic effort to prevent further escalation and stabilize the region. The outcome of the talks, regardless of the case, was expected to have significant implications for regional security, global energy markets, and international diplomatic relations. Pakistan's unlikely rise as a mediator in the conflict led to notice and discussion.
== Definition, regulatory aspects == The International Council on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use, a 2015 Swiss NGO of pharmaceutical companies and others, defined a contract research organization (CRO), specifically pertaining to clinical trials services as: "A person or an organization (commercial, academic, or other) contracted by the sponsor to perform one or more of a sponsor's trial-related duties and functions." It further details the sponsor's responsibilities in its good clinical practice guidelines:
Sources: en.wikipedia.org
It acts as a dual agonist at the GIP receptor and the GLP-1 receptor. This broader targeting profile distinguishes it from selective GLP-1 agonists, which engage only one receptor.
A fatty diacid side chain promotes binding to albumin, which delays clearance from circulation. The half-life of roughly five days makes a weekly schedule practical.
No. It is a synthetic peptide whose backbone is based on the natural incretin hormone GIP. Non-natural residues and the lipid side chain were engineered to improve stability and duration of action.
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。