The short version of 脂肪酸侧链 fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-01-27. Anything still debated is marked as such rather than presented as settled.
Like most synthetic peptides of this size, the material is commonly supplied as a lyophilised powder that appears white to off-white. It dissolves in aqueous buffers and in mixtures of water with a small proportion of organic solvent, though the fatty acid portion reduces solubility in pure water relative to short peptides. Hygroscopic behaviour is reported for many peptide powders, so weighing is usually performed quickly and under controlled humidity. Working solutions are typically prepared fresh and kept cold.
Long-term storage of lyophilised peptide powder is generally at minus twenty degrees Celsius or colder, with desiccant and protection from light. Short-term storage at two to eight degrees Celsius is common during active use. In solution, stability depends strongly on pH, concentration, and the presence of preservatives, and hydrolysis or aggregation can develop over weeks. Published stability data specific to this molecule are limited, so recommended conditions for research material are usually extrapolated from general peptide handling practice rather than from a dedicated study.
Bulk peptide material is normally characterised by reversed-phase high-performance liquid chromatography, which separates the target sequence from truncation products and other closely related impurities. Ultraviolet detection near 214 nanometres is common because the peptide backbone absorbs in that region. Mass spectrometry, usually electrospray ionisation coupled to a mass analyser, is used to confirm the molecular mass. Because the molecule carries a lipophilic side chain, gradient methods often need a relatively high organic modifier fraction to elute it within a practical retention window.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Visual inspection |
| Solubility | Soluble in aqueous buffer | Lipophilic chain lowers pure-water solubility |
| Long-term storage | -20 degrees Celsius or lower | With desiccant, protected from light |
| Short-term storage | 2 to 8 degrees Celsius | For dissolved aliquots |
| Typical purity method | Reversed-phase HPLC | Ultraviolet detection, often with mass confirmation |
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.
Clinical research programs have evaluated tirzepatide in adults with type 2 diabetes and in adults with obesity or excess weight. Trials generally reported reductions in glycated hemoglobin and body weight across treatment periods of several months. Since these studies enrolled defined populations under controlled conditions, the findings describe group averages rather than individual outcomes. Open questions include the durability of effects after treatment stops, variation among subgroups, and the long-term consequences of sustained dual receptor stimulation. Published trial summaries should be consulted for exact measurements rather than secondary accounts.
Tirzepatide is a synthetic peptide built from 39 amino acid residues. Its backbone derives from the native glucose-dependent insulinotropic polypeptide sequence, altered at several positions to resist enzymatic cleavage. A fatty diacid group attached through a linker extends plasma residence time by promoting reversible binding to serum albumin. The molecule carries a net negative charge near physiological pH and has a reported molecular weight close to 4813 daltons. These features separate it from shorter incretin analogs and account for its prolonged dosing interval.
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。
Firefighters hit the demonstrators with powerful water cannons, and the police continued to beat and arrest people. Protesters managed to build a defensible barricade in front of the Dunărea ("Danube") restaurant, which stood until after midnight, but was finally torn apart by government forces. Intense shooting continued until after 03:00, by which time the survivors had fled the streets. Records of the fighting that day include footage shot from helicopters that were sent to raid the area and record evidence for eventual reprisals, as well as by tourists in the high tower of the centrally located InterContinental Hotel, next to the National Theatre and across the street from the university. It is likely that in the early hours of 22 December that the Ceaușescus made their second mistake. Instead of fleeing the city under cover of night, they decided to wait until morning to leave. Ceaușescu must have thought that his desperate attempts to crush the protests had succeeded, because he apparently called another meeting for the next morning. However, before 07:00, his wife Elena received the news that large columns of workers from many industrial platforms (large communist-era factories or groups of factories concentrated into industrial zones) were heading towards the city centre of Bucharest to join the protests. The police barricades that were meant to block access to Piața Universității (University Square) and Palace Square proved useless. By 09:30 University Square was jammed with protesters.
=== Culinary use === The leaves and shoots can be eaten raw, having a bitter flavor. They can also be cooked like spinach or are sometimes added to salads. An extract is sometimes added as a flavoring in vodkas.
The skin permeability of a compound is based on its physicochemical properties, particularly lipophilicity and hydrophilicity. In general, the more polar groups, for instance hydroxyl groups, that are present in a steroid, and hence the more hydrophilic and less lipophilic it is, the lower its skin permeability. For this reason, progesterone and estrone have higher skin permeability, estradiol has moderate skin permeability, and estriol and cortisol have lower skin permeability. The transdermal bioavailability of progesterone applied to the breasts is approximately 10%. This is roughly the same as that of the general transdermal absorption of estradiol and testosterone, although applied to other skin sites. The site of application of transdermal progesterone may influence its absorption. A study observed a significant increase in circulating levels of progesterone shortly after administration when it was applied as a transdermal ointment to the breasts but not when it was applied to other areas like the thigh or abdomen. Whereas estradiol circulates at levels in the picomolar range (pg/mL), progesterone circulates at concentrations in the nanomolar range (ng/mL), and a relatively large dose is required to produce these levels. The body synthesizes about 25 mg of progesterone per day on average during the luteal phase. This relatively large quantity by weight has been claimed to require around 50% of the body to be used as a surface of absorption to deliver a similar quantity of progesterone on the basis of its absorption mechanics.
=== 26 March === The SAF retook Khartoum International Airport and the Manshiya Bridge over the Blue Nile in Khartoum. It also retook the Tiba al-Hassanab camp in Jabal Aulia, which is described as the RSF's last stronghold in Khartoum and its main base in central Sudan. Al-Burhan visited the presidential palace in Khartoum and announced the liberation of the city, proclaiming that "Khartoum is free".
Although increases in immunoglobulins usually increase the ESR, very high levels can reduce it again due to hyperviscosity of the plasma. This is especially likely with IgM-class paraproteins, and to a lesser extent, IgA-class. The basal ESR is slightly higher in females.
Sources: en.wikipedia.org
Opioids are a class of drugs that derive from, or mimic, natural substances found in the opium poppy plant. Opioids work on opioid receptors in the brain and other organs to produce a variety of morphine-like effects, including pain relief. The terms opioid and opiate are sometimes used interchangeably, but the term opioid is often used to designate all substances, both natural and synthetic, that bind to opioid receptors in the brain, while the term opiate is often used to refer to alkaloid compounds naturally found in the opium poppy plant Papaver somniferum. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use disorder, and suppressing cough. The opioid receptor antagonist naloxone is used to reverse opioid overdose. Extremely potent opioids such as carfentanil are approved only for veterinary use. Opioids are also frequently used recreationally for their euphoric effects or to prevent withdrawal. Opioids can be fatal, and have been used, alone and in combination, in a small number of executions in the United States. Side effects of opioids may include itchiness, sedation, nausea, respiratory depression, constipation, and euphoria. Long-term use can cause tolerance, meaning that increased doses are required to achieve the same effect, and physical dependence, meaning that abruptly discontinuing the drug leads to unpleasant withdrawal symptoms. The euphoria attracts recreational use; frequent, escalating recreational use of opioids typically results in addiction.
=== Notable users === József Knoll, one of the developers of selegiline, began taking a low 1 mg daily dose of selegiline on January 1, 1989, at the age of 64. He reported in 2012 that this had continued for 22 years uninterrupted. Knoll stated that he had become so fascinated with the possible longevity-promoting effects of selegiline that he had decided to start taking it as a self-experiment. Knoll later died in 2018 at the age of 93. David Pearce, a British transhumanist philosopher, wrote his self-published book-length internet manifesto The Hedonistic Imperative six weeks after starting to take selegiline. Hamilton Morris, a psychoactive drug journalist and researcher, appears to have used selegiline. Sam Bankman-Fried, the founder and former CEO of the FTX cryptocurrency exchange, is known to have used selegiline for depression in the form of the Emsam patch for at least 5 to 10 years. He is also known to have simultaneously taken Adderall for treatment of attention deficit hyperactivity disorder (ADHD) and to have possessed non-pharmaceutical adrafinil, a prodrug of modafinil.
known as dissociation in the context of acid–base reactions. The chemical species HA is an acid that dissociates into A−, called the conjugate base of the acid, and a hydrogen ion, H+. The system is said to be in equilibrium when the concentrations of its components do not change over time, because both forward and backward reactions are occurring at the same rate. The dissociation constant is defined by
On March 31, 2011, Priszm, who was the largest franchisee of KFC restaurants in Canada at the time, went into bankruptcy protection in Ontario and British Columbia. By 2015, KFC was struggling, having lost business to other retailers and being surpassed by Chick-fil-A as the leading chicken retailer in the US three years previously. The company launched a new initiative with a plan to revamp its packaging, decor and uniforms and expand its menu. Additionally, beginning in May 2015, a new series of US advertisements was launched featuring Darrell Hammond as Colonel Sanders. In a planned rotation of actors, Norm Macdonald, Jim Gaffigan, George Hamilton and Rob Riggle portrayed Sanders in similar ads through the fall of 2016. In January 2018, country music icon Reba McEntire played the first female Colonel Sanders. Before leaving as CEO in 2021, Andrea Zahumensky told Ad Age the "brand assets that we're so lucky to have" were the bucket, the three stripes and the full name Kentucky Fried Chicken. All of these were being used more by the chain. Australia rebranded KFC back to its original name, "Kentucky Fried Chicken" in 2019. In June 2026, KFC unveiled a global refresh that included updated visual branding, revised restaurant designs, and new menu offerings across its international operations.
Sources: en.wikipedia.org
AlphaKnot complements KnotProt, a database focused on experimentally determined protein structures and their topological features. KnotProt provides detailed descriptions of knots, slipknots, and related entanglements in experimentally characterized proteins, whereas AlphaKnot was developed primarily to examine the much larger population of structures generated by modern protein-structure prediction methods. AlphaKnot has been used to investigate the frequency and distribution of knots in protein families and to identify previously uncharacterized topological architectures. Large-scale analyses of AlphaFold structures have identified unusual knot types and proteins containing multiple knots, while comparison with experimentally determined structures has provided examples in which unusual predicted topologies were subsequently confirmed experimentally. The database can therefore be used both as a source of candidate knotted proteins for experimental investigation and as a computational tool for examining the relationship between protein sequence, structure, and topology.
In terms of dosage equivalence, norethisterone and NETA are typically used at respective dosages of 0.35 mg/day and 0.6 mg/day as progestogen-only contraceptives, and at respective dosages of 0.5–1 mg/day and 1–1.5 mg/day in combination with ethinylestradiol in combined oral contraceptives. Conversely, the two drugs have been used at about the same dosages in menopausal hormone therapy for the treatment of menopausal symptoms. NETA is of about 12% higher molecular weight than norethisterone due to the presence of its C17β acetate ester. Micronization of NETA has been found to increase its potency by several-fold in animals and women. The endometrial transformation dosage of micronized NETA per cycle is 12 to 14 mg, whereas that for non-micronized NETA is 30 to 60 mg.
The tine test, which uses a "button" with four to six short needles coated with tuberculin instead of an injection. It is easier to administer. It has comparable results if "doubtful" indications are treated as positive. The US CDC and the American Thoracic Society believe that it is less reliable because the amount of tuberculin that enters the skin cannot be accurately determined, despite the aforementioned results. The Heaf test, a test similar to the tine test formerly used in the United Kingdom. A spring-loaded instrument with six needles is used. It stopped being used in 2005 as the manufacturer deemed the production of this instrument financially unsustainable.
Romanowsky was the first to realise the differences in the staining abilities of eosin and methylene blue. The individual stains (monochromatic staining) were good only for general colouring of tissue or cell, but not for contrasting the different components. By mixing specific amount of eosin and methylene blue, Romanowsky found that the mixture gave images of contrasting clarity that helped to visualise different parts and components of cells. This mixture method, polychromatic staining or polychromy, with various modifications became the most efficient way of staining cells for identifying cellular components. The chemical phenomenon by which a mixture of stains produces vibrant cell images is known as "Romanowsky effect". In December 1890, Romanowsky published his invention as a preliminary report of his major work for his doctoral thesis in the journal Vrach as "On the question of the structure of malaria parasites" (as translated in English). Incorrectly, it is more often recorded in books and journals that Romanowsky published his findings in 1891, which led to a controversy on priority that Ernst Malachowsky independently developed the technique as the latter published his research in August 1891.
The patient must then wait about an hour for the sugar to distribute and be taken up into organs which use glucose – a time during which physical activity must be kept to a minimum, in order to minimize uptake of the radioactive sugar into muscles (this causes unwanted artifacts in the scan, interfering with reading especially when the organs of interest are inside the body vs. inside the skull). Then, the patient is placed in the PET scanner for a series of one or more scans which may take from 20 minutes to as long as an hour (often, only about one-quarter of the body length may be imaged at a time).
Sources: en.wikipedia.org
It separates molecules by hydrophobicity, which is effective for distinguishing an intact peptide from truncated or chemically modified forms. A C18 column with an acidic water-organic mobile phase is a standard configuration.
Lyophilised powder is generally held at minus twenty degrees Celsius or lower for long-term storage. Once dissolved, aliquots are kept at two to eight degrees Celsius for short periods and should not be repeatedly frozen and thawed.
Photo-oxidation can modify tryptophan, methionine, and tyrosine residues, altering the structure. Amber glass containers or foil wrapping are routine measures to reduce light exposure.
It is normally kept frozen, desiccated, and away from light, with brief warming to room temperature before opening to limit condensation. Repeated freeze-thaw cycles are avoided because they stress the peptide. Once in solution, the material is held cold and used promptly.