Everything below concerns incretin. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-05-15. Where a claim depends on a specific study, the study is described rather than over-claimed.
Tirzepatide is a synthetic peptide built from 39 amino acid residues. Its sequence is related to human glucose-dependent insulinotropic polypeptide, with modifications that include a C-terminal extension and a C20 fatty diacid joined through a linker. Those changes raise the molecule's affinity for serum albumin, which slows renal filtration and lengthens the time it stays in circulation. The free base has an average molecular mass near 4813.5 daltons. The compound is made by solid-phase peptide synthesis followed by chromatographic purification.
At the receptor level, tirzepatide activates both the glucose-dependent insulinotropic polypeptide receptor and the glucagon-like peptide-1 receptor. Both belong to the class B family of G protein-coupled receptors and signal largely through cyclic AMP accumulation. The compound binds the two receptors with differing affinity, and the pattern of signaling at each site is described in the literature as biased rather than simply proportional to occupancy. Tissues carrying these receptors include pancreatic islets, adipose tissue, the central nervous system, and the gastrointestinal tract. The relative weight of each receptor population in producing metabolic effects continues to be studied.
Published work supports the view that engaging two incretin receptors produces changes in glucose handling and body weight larger than those seen with single-receptor activation. Why that difference arises is not fully settled. Open questions include how much of the observed weight effect depends on central versus peripheral signaling, and whether the two receptors form interacting complexes. Most reported findings come from controlled trials and animal models, and translation between species is imperfect. Further research is expected to refine these points over time.
定量分析的主流方法是反相高效液相色谱联用紫外或质谱检测，利用肽在疏水固定相上的保留行为确定纯度与含量。对于生物基质中的浓度测定，常采用液相色谱串联质谱，并配合固相萃取或蛋白沉淀进行样品前处理。免疫分析法也可使用，但可能受到结构相关肽的交叉反应干扰。
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。
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C225H348N48O68 | 39-residue synthetic peptide |
| Average molecular mass | About 4813.5 Da | Free base form |
| Appearance | White to off-white powder | Solid after lyophilization |
| Solubility class | Freely soluble in water | Also soluble in neutral aqueous buffers |
| Typical storage | At or below -20 °C, desiccated | Protect from light and moisture |
Clinical development proceeded through large phase 3 programmes in type 2 diabetes and in obesity or overweight with at least one weight-related comorbidity. Regulatory approvals followed in several jurisdictions for both indications. Weekly subcutaneous dosing reflects an elimination half-life of roughly five days. Open questions include the durability of metabolic effects after treatment stops, long-term cardiovascular and hepatic outcomes beyond completed trials, and whether the dual mechanism confers benefits independent of total receptor occupancy. Published literature continues to expand on these points. Substantial uncertainty remains about interindividual variability in response.
Tirzepatide is a synthetic linear peptide of 39 amino acids that acts as a dual agonist at the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors. Its sequence derives from native GIP but incorporates non-natural residues and a C20 fatty diacid moiety linked to a lysine side chain. The lipophilic chain promotes albumin binding, which slows renal clearance and extends circulation time. The unmodified peptide has a molecular formula of C225H348N48O68 and a molecular mass near 4,813 daltons.
Receptor activation by tirzepatide raises intracellular cyclic AMP through Gs-coupled signalling at both targets. At the GLP-1 receptor the downstream effect includes glucose-dependent insulin release, suppressed glucagon secretion, delayed gastric emptying, and reduced appetite signalling in the hypothalamus. GIP receptor engagement adds insulinotropic activity and appears to influence lipid handling in adipose tissue. Because both receptors are stimulated at the same time, the pharmacological profile differs from that of selective GLP-1 receptor agonists, and the relative contribution of each arm remains an area of active investigation.
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.
Tirzepatide is a synthetic peptide of 39 amino acids that carries a C20 fatty diacid side chain attached through a linker. Its molecular formula is C225H348N48O68, and its molecular weight is about 4813 daltons. The compound belongs to the incretin mimetic class and is administered by subcutaneous injection. The fatty acid chain promotes binding to serum albumin, which slows renal clearance and extends the circulation time of the molecule. It was identified during screening of sequences derived from glucose-dependent insulinotropic polypeptide.
Tirzepatide activates both the glucose-dependent insulinotropic polypeptide receptor and the glucagon-like peptide-1 receptor, making it a dual agonist rather than a selective agent. Engagement of the GLP-1 receptor is linked to glucose-dependent insulin release, slower gastric emptying, and reduced appetite signalling. The relative contribution of the GIP arm remains an active research question; proposed roles include improved insulin sensitivity and altered adipose tissue handling. Receptor occupancy studies suggest the molecule interacts with both targets at circulating concentrations achieved during therapy.
The king cobra (Ophiophagus hannah) is the longest venomous snake in the world, and it can inject very high volumes of venom in a single bite. The venom LD50 is 1.80 mg/kg SC according to Broad et al. (1979). The mean value of subcutaneous LD50 of five wild-caught king cobras in Southeast Asia was determined to be 1.93 mg/kg. Between 350 and 500 mg (dry weight) of venom can be injected at once (Minton, 1974). In another study by Broad et al. (1979), the average venom quantity was 421 mg (dry weight of milked venom). The maximum venom yield is approximately 1000 mg (dry weight). The king cobra has a fearsome reputation. When annoyed, it spreads a narrow hood and growls loudly, but some scientists claim that their aggressiveness is grossly exaggerated. In most of the local encounters with live, wild king cobras, the snakes appear to be of rather placid disposition, and they usually end up being killed or subdued with hardly any histrionics. These support the view that wild king cobras generally have a mild temperament, and despite their frequent occurrence in disturbed and built-up areas, are adept at avoiding humans. Naturalist Michael Wilmer Forbes Tweedie felt that "this notion is based on the general tendency to dramatise all attributes of snakes with little regard for the truth about them. A moment's reflection shows that this must be so, for the species is not uncommon, even in populated areas, and consciously or unconsciously, people must encounter king cobras quite frequently.
==== States and territories ==== Lower houses members of the Legislative Assemblies of New South Wales, Queensland and Victoria, and the Houses of Assembly in South Australia and Tasmania use the post-nominal "MP". Previously, these states used the post-nominals "MLA" ("Member of the Legislative Assembly") and "MHA" ("Member of the House of Assembly") respectively. Members of the Legislative Assemblies of Western Australia, Northern Territory, and Australian Capital Territory use the post-nominal "MLA". However, "MP" is also commonly used. In bicameral legislatures, members of the upper house (legislative council) use "MLC" ("Member of the Legislative Council"). MLCs are informally referred to as upper house MPs.
== Cell types and locations == The spleen is the second largest unit of the mononuclear phagocyte system. The monocyte is formed in the bone marrow and transported by the blood; it migrates into the tissues, where it transforms into a histiocyte or a macrophage. Macrophages are diffusely scattered in the connective tissue and in liver (Kupffer cells), spleen and lymph nodes (sinus histiocytes), lungs (alveolar macrophages), and central nervous system (microglia). The half-life of blood monocytes is about 1 day, whereas the life span of tissue macrophages is several months or years. The mononuclear phagocyte system is part of both humoral and cell-mediated immunity. The mononuclear phagocyte system has an important role in defense against microorganisms, including mycobacteria, fungi, bacteria, protozoa, and viruses. Macrophages remove senescent erythrocytes, leukocytes, and megakaryocytes by phagocytosis and digestion.
=== Use in crime === The Z-drugs, including zolpidem, have been used as date rape drugs. Zolpidem is available by prescription, and broadly prescribed unlike other date rape drugs: gamma-hydroxybutyrate (GHB), which is used to treat narcolepsy, or flunitrazepam (Rohypnol), which is only prescribed as a second-line choice for insomnia. Zolpidem can be detected in bodily fluids for 36 hours, though it may be possible to detect it by hair testing much later, which is due to the short elimination half-life of 2.5–3 hours. This use of the drug was highlighted during proceedings against Darren Sharper, who was accused of using the tablets he was prescribed to facilitate a series of rapes.
Sources: en.wikipedia.org
== Prizes and honours == 1997, 1999 Merit scholarship to study Medical Laboratory Technology at Institute of Medicine, Tribhuvan University 2005 Gallwas membership Grant, AACC 2005 and 2007 International travel grant, AACC 2006 Young Achievers Award 2007 International Travel Grant, Asian & Pacific Federation of Clinical Biochemistry (APFCB) 2008 and 2010 KNU Honors Scholarship for Graduation Study (MS and PHD) 2012 Featured member of AACC, interview published at AACC website 2013 KNU Best Publication Award 2014 KNU Cell-Matrix Research Institute Winter Seminar Award
=== Pharmacokinetics === Ketamine is effectively metabolized by the superfamily of cytochrome P450 enzymes, particularly CYP2B6 and CYP3A. Though these enzymes are predominantly found in the liver, they are present in many other organs and tissue groups throughout the body, localized to the endoplasmic reticulum of such cells. Peak concentration of norketamine occurs roughly 17 minutes after initially administering ketamine. The subsequent metabolism of norketamine to hydroxynorketamine and dehydronorketamine from ketamine occurs 2–3 hours after ketamine infusion, and occurs at a roughly 30:70 formation ratio. HNK is formed via the hydroxylation of the cyclohexone ring; these are then conjugated with glucoronic acid to form DHNK. As with their precursors ketamine and norketamine, HNK and DHNK are of great interest to pharmacologists for their putative anti-depressant and analgesic properties.
=== Atherosclerosis === Rapamycin can accelerate degradation of oxidized LDL cholesterol in endothelial cells, thereby lowering the risk of atherosclerosis. Oxidized LDL cholesterol is a major contributor to atherosclerosis.
== Iron malabsorption == Instant coffee decreases intestinal iron absorption more than drip coffee. One study estimated that, when a cup of instant coffee was ingested with a meal composed of semi-purified ingredients, intestinal absorption was reduced from 5.88% to 0.97%, compared to an absorption of 1.64% with drip coffee. It was also estimated that, when the strength of the instant coffee was doubled, intestinal iron absorption fell to 0.53%. However, there is no decrease in iron absorption when instant coffee is consumed 1 hour before a meal, but the same degree of inhibition as with simultaneous ingestion occurs when instant coffee is taken 1 hour after a meal.
South Africa gradually became locked in a conventional arms race with Angola; each side argued that it had to match the increased force available to the other. To counter the appearance of advanced MiG-23 and SU-22 fighters in Angola, for instance, South Africa began development on two sophisticated fighter aircraft of its own, the Atlas Cheetah and the Atlas Carver. Both programmes would consume billions of rand.
Sources: en.wikipedia.org
nonsense mutation Also point-nonsense mutation. A type of point mutation which results in a premature stop codon in the transcribed mRNA sequence, thereby causing the premature termination of translation, which results in a truncated, incomplete, and often non-functional protein.
== Research == Flupirtine has been noted for its neuroprotective properties, and has been investigated for possible use in Creutzfeldt–Jakob disease, Alzheimer's disease, and multiple sclerosis. It has also been proposed as a possible treatment for Batten disease. Flupirtine underwent a clinical trial as a treatment for multiple sclerosis and fibromyalgia. Flupirtine showed promise for fibromyalgia due to its different action than the three approved by U.S. FDA drugs: pregabalin, milnacipran, and duloxetine. Additionally, there are case reports regarding flupirtine as a treatment for fibromyalgia. Adeona Pharmaceuticals (now called Synthetic Biologics) sub-licensed its patents for using flupirtine for fibromyalgia to Meda AB in May 2010.
Elongation factors are part of the mechanism that synthesizes new proteins through translation in the ribosome. Transfer RNAs (tRNAs) carry the individual amino acids that become integrated into a protein sequence, and have an anticodon for the specific amino acid that they are charged with. Messenger RNA (mRNA) carries the genetic information that encodes the primary structure of a protein, and contains codons that code for each amino acid. The ribosome creates the protein chain by following the mRNA code and integrating the amino acid of an aminoacyl-tRNA (also known as a charged tRNA) to the growing polypeptide chain. There are three sites on the ribosome for tRNA binding. These are the aminoacyl/acceptor site (abbreviated A), the peptidyl site (abbreviated P), and the exit site (abbreviated E). The P-site holds the tRNA connected to the polypeptide chain being synthesized, and the A-site is the binding site for a charged tRNA with an anticodon complementary to the mRNA codon associated with the site. After binding of a charged tRNA to the A-site, a peptide bond is formed between the growing polypeptide chain on the P-site tRNA and the amino acid of the A-site tRNA, and the entire polypeptide is transferred from the P-site tRNA to the A-site tRNA. Then, in a process catalyzed by the prokaryotic elongation factor EF-G (historically known as translocase), the coordinated translocation of the tRNAs and mRNA occurs, with the P-site tRNA moving to the E-site, where it dissociates from the ribosome, and the A-site tRNA moves to take its place in the P-site.
Each chemical element has a unique atomic number (Z— for "Zahl", German for "number") representing the number of protons in its nucleus. Each distinct atomic number therefore corresponds to a class of atom: these classes are called the chemical elements. The chemical elements are what the periodic table classifies and organizes. Hydrogen is the element with atomic number 1; helium, atomic number 2; lithium, atomic number 3; and so on. Each of these names can be further abbreviated by a one- or two-letter chemical symbol; those for hydrogen, helium, and lithium are respectively H, He, and Li. Neutrons do not affect the atom's chemical identity, but do affect its weight. Atoms with the same number of protons but different numbers of neutrons are called isotopes of the same chemical element. Naturally occurring elements usually occur as mixes of different isotopes; since each isotope usually occurs with a characteristic abundance, naturally occurring elements have well-defined atomic weights, defined as the average mass of a naturally occurring atom of that element. All elements have multiple isotopes, variants with the same number of protons but different numbers of neutrons. For example, carbon has three naturally occurring isotopes: all of its atoms have six protons and most have six neutrons as well, but about one per cent have seven neutrons, and a very small fraction have eight neutrons. Isotopes are never separated in the periodic table; they are always grouped together under a single element.
Sources: en.wikipedia.org
It is a synthetic peptide and a dual agonist of two incretin receptors. It is not a small molecule, and it is not structurally related to the older single-receptor peptide agonists.
The C20 fatty diacid promotes tight binding to serum albumin. That binding reduces renal clearance and extends circulation time compared with an unmodified peptide of similar length.
It is not fully established. Studies indicate that both receptors contribute to the observed effects, but the exact split between the two signaling pathways in humans remains an open question.
建议在低温、避光、干燥环境中密封保存，常见条件为 2 至 8 摄氏度，长期存放可置于更低温度。应避免反复冻融，并尽量减少容器开启次数。