This is a working overview of selectivity, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-06-09. Anything still debated is marked as such rather than presented as settled.
Ipamorelin is a synthetic pentapeptide classified as a growth hormone secretagogue. Its sequence, Aib-His-D-2-Nal-D-Phe-Lys-NH2, combines three non-proteinogenic residues with a C-terminal amide. The N-terminal aminoisobutyric acid unit and the two aromatic D-amino acids distinguish it from peptides assembled only from standard L-amino acids. Its formula is C38H49N9O5, corresponding to an average mass near 711.9 Da. At neutral pH the molecule carries a net positive charge, a property that shapes its behaviour in chromatographic and electrophoretic systems.
The compound was developed at Novo Nordisk during the 1990s as part of a programme seeking secretagogues with improved selectivity. It was described in the peer-reviewed literature in 1998 alongside related pentapeptides from the same series. Investigators advanced it because it raised growth hormone output in animal models while leaving other pituitary hormones comparatively unaffected. The development code NNC 26-0161 appears in earlier reports, and ipamorelin later became the common designation in published work.
Selectivity is the property most often attached to this peptide. Published animal and early human studies record increases in growth hormone release after administration, with adrenocorticotropic hormone and cortisol responses remaining small by comparison. Effects on appetite-related pathways also appear weaker than those reported for several earlier secretagogues. Reviews that compare members of the growth hormone secretagogue family cite these findings frequently, though the receptor-level explanation for the selectivity continues to be debated rather than settled.
Ipamorelin 是一种合成五肽，在 20 世纪 90 年代被报道为生长激素促分泌剂。其结构基于胃饥饿素受体激动剂的设计思路，但并非天然激素。早期药理学研究显示，它可刺激垂体释放生长激素，而对应激激素轴的影响相对较小。该化合物常被用作研究生长激素调节通路的工具分子。
在机制层面，ipamorelin 与生长激素促分泌受体 1a 型结合，该受体也介导胃饥饿素的多种效应。受体激活后，细胞内信号促进生长激素从垂体前叶释放。由于对促肾上腺皮质激素和皮质醇的刺激较弱，它被视为选择性较高的促分泌剂。这种选择性在动物模型和少量人体研究中被观察到，但人体数据仍然有限。
现有文献多来自小规模、短期的研究，涉及生长激素缺乏、术后肠麻痹等方向。长期使用是否导致受体脱敏，以及重复给药后效应是否衰减，仍属开放问题。不同研究之间的剂量、给药途径和受试者特征差异较大，因此结论外推需谨慎。关于临床获益的确切证据尚不充分，需要更大规模的对照试验来澄清。
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H49N9O5 | Pentapeptide with C-terminal amide |
| Average mass | Approximately 711.9 Da | Value derived from the formula |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and aqueous acetonitrile | Dissolution aided by acidic diluents |
| Common synonyms | Ipamorelin; NNC 26-0161 | Code name used in early reports |
Ipamorelin is a synthetic pentapeptide that acts as an agonist at the ghrelin receptor, also called the growth hormone secretagogue receptor type 1a. Its sequence incorporates non-natural residues, which slows enzymatic breakdown relative to short native peptides. In laboratory and early clinical work the compound is described as a selective growth hormone secretagogue because it raises growth hormone with comparatively little effect on other pituitary outputs. The degree to which that selectivity holds across species and dosing regimens remains an open question in the published literature.
Signal transduction begins when the peptide binds GHSR-1a on pituitary somatotrophs. The receptor couples to Gq/11 proteins, activating phospholipase C, which cleaves phosphatidylinositol bisphosphate into inositol trisphosphate and diacylglycerol. Inositol trisphosphate releases calcium from intracellular stores, and the resulting rise in cytosolic calcium drives growth hormone vesicle fusion. Concurrent Gs coupling and cyclic AMP elevation have also been reported, and the relative contribution of each arm to the overall secretory response is not fully settled.
Storage recommendations for the dry solid center on low temperature and low moisture, most often -20 °C in a sealed, desiccated container protected from light. Solutions are less stable than the powder and are usually kept cold and used within a short window. Freeze-thaw cycling is a recognized source of loss, and aliquoting before freezing is a standard precaution. These practices derive from general peptide handling principles rather than from a single published stability trial, so exact shelf lives should be treated as approximate.
Analytical confirmation relies on reversed-phase high-performance liquid chromatography, often coupled to mass spectrometry for identity and purity assessment. Mass spectrometry distinguishes the intact molecule from truncation products and from oxidation or deamidation variants that share similar chromatographic retention. Immunoassays appear in some biological studies but can cross-react with related peptides, so they are weaker tools for identity work. Reported purity figures depend heavily on the gradient, detector, and integration method used, which complicates direct comparison between laboratories.
==== Caribbean and Latin America ==== Cream soda is usually served as a "red pop", particularly Fanta's Red Cream Soda. Champagne cola (also spelled "kola"), a soft drink similar to cream soda, is ubiquitous across the region. In the Caribbean there are several popular brands of clear, vanilla-flavored cream soda.
==== Organically sourced micronutrients ==== Micronutrients can be sourced from organic fertilizers as well. For example, composted pine bark is high in manganese and is sometimes used to fulfill that mineral requirement in conventional hydroponic solutions. To satisfy requirements for National Organic Programs, pulverized, unrefined minerals (e.g. Gypsum, Calcite, and glauconite) can also be added to satisfy a plant's nutritional needs.
==== Root parsley ==== Another type of parsley is grown as a root vegetable, the Hamburg root parsley (P. crispum Radicosum Group, syn. P. crispum var. tuberosum). This type of parsley produces much thicker roots than types cultivated for their leaves. Although seldom used in Britain and the United States, root parsley is common in central and eastern European cuisine, where it is used in soups and stews, or simply eaten raw, as a snack (similar to carrots). Although root parsley looks similar to the parsnip, which is among its closest relatives in the family Apiaceae, its taste is quite different.
Sources: en.wikipedia.org
=== mEos2 === mEosFP is another monomeric Eos variant that folds effectively at 37 degrees Celsius. Where tdEos (tandem dimer) cannot fuse to targets such as histones, tubulin, intermediate filaments and gap junctions, and mEos (monomeric) which can only be used successfully at 30 degrees Celsius, mEos2 is an engineered variant that can fold effectively at 37 degrees Celsius and successfully label targets intolerant to fusion from other fluorescent protein dimers . mEos2 shows almost identical spectral properties, brightness, pKa, photoconversion, contrast and maturation properties to WT Eos. The localization precision of mEos2 is twice as great as other monomeric fluorescent proteins.
A neuron is called identified if it has properties that distinguish it from every other neuron in the same animal—properties such as location, neurotransmitter, gene expression pattern, and connectivity—and if every individual organism belonging to the same species has exactly one neuron with the same set of properties. In vertebrate nervous systems, very few neurons are "identified" in this sense. Researchers believe humans have none—but in simpler nervous systems, some or all neurons may be thus unique. In vertebrates, the best known identified neurons are the gigantic Mauthner cells of fish. Every fish has two Mauthner cells, located in the bottom part of the brainstem, one on the left side and one on the right. Each Mauthner cell has an axon that crosses over, innervating (stimulating) neurons at the same brain level and then travelling down through the spinal cord, making numerous connections as it goes. The synapses generated by a Mauthner cell are so powerful that a single action potential gives rise to a major behavioral response: within milliseconds the fish curves its body into a C-shape, then straightens, thereby propelling itself rapidly forward. Functionally of this is a fast escape response, triggered most easily by a strong sound wave or pressure wave impinging on the lateral line organ of the fish. Mauthner cells are not the only identified neurons in fish—there are about 20 more types, including pairs of "Mauthner cell analogs" in each spinal segmental nucleus.
There are hydrophobic amino acids and hydrophilic amino acids in protein molecules. After protein folding in aqueous solution, hydrophobic amino acids usually form protected hydrophobic areas while hydrophilic amino acids interact with the molecules of solvation and allow proteins to form hydrogen bonds with the surrounding water molecules. If enough of the protein surface is hydrophilic, the protein can be dissolved in water. When salt is added to the solution, there is more frequent interaction between solvent molecules and salt ions. As a result, the protein and salt ions compete to interact with the solvent molecules with the result that there are fewer solvent molecules available for interaction with the protein molecules than before. The protein–protein interactions thus become stronger than the solvent–solute interactions and the protein molecules associate by forming hydrophobic interactions with each other. After dissociation in a given solvent, the negatively charged atoms from a chosen salt begin to compete for interactions with positively charged molecules present in the solution. Similarly, the positively charged cations compete for interactions with the negatively charged molecules of the solvent. This process is known as salting out. Soaps are easily precipitated by concentrated salt solution, the metal ion in the salt reacts with the fatty acids forming back the soap and glycerin (glycerol). To separate glycerin from the soap, the pasty boiling mass is treated with brine (NaCl solution).
Sources: en.wikipedia.org
Symmetrical selenides are usually prepared by alkylation of alkali metal selenide salts, e.g. sodium selenide. Unsymmetrical selenides are prepared by alkylation of selenoates. These compounds typically react as nucleophiles, e.g. with alkyl halides (R'−X) to give selenonium salts [RR'R"Se]+X−. Divalent selenium can also interact with soft heteroatoms to form hypervalent selenium centers. They also react in some circumstances as electrophiles, e.g. with organolithium reagents (R'Li) to the ate complex R'RRSe−Li+. Selenoxides (R−Se(=O)−R) are the selenium equivalents of sulfoxides. Most are unstable, undergoing the selenoxide elimination, but can be notionally oxidized to selenones R−Se(=O)2−R, the selenium analogues of sulfones. Selenenic acid (R−Se−OH) are intermediates in the oxidation of selenols. They occur in some selenoenzymes, such as glutathione peroxidase. Seleninic acids (R−Se(=O)−OH) are analogues of sulfinic acids. Selenonic acids (R−Se(=O)2−OH) are analogues of sulfonic acids. Peroxyseleninic acids (R−Se(=O)−OOH) catalyse epoxidation reactions and Baeyer–Villiger oxidations. Selenuranes are hypervalent organoselenium compounds, formally derived from the tetrahalides such as SeCl4. Examples are of the type Ar−SeCl3. The chlorides are obtained by chlorination of the selenenyl chloride. Seleniranes are three-membered rings (the parent compound is selenirane or selenacyclobutane C2H4Se) related to thiiranes but, unlike thiiranes, seleniranes are kinetically unstable, extruding selenium directly (without oxidation) to form alkenes.
== Etymology == The term was coined in 1995 from cathelin, due to the characteristic cathelin-like domain present in cathelicidins. The name cathelin itself is coined from cathepsin L inhibitor in 1989.
== Supplementation == α-Ketoglutaric acid is naturally generated and consumed via the citric acid cycle. Nevertheless, studies that are primarily preclinical (i.e., conducted in animal models of disease or on animal or human tissues) have examined the effects of adding this molecule to biological systems in amounts beyond what is naturally present. Middle‐aged, i.e., 10‐month‐old, mice had lower serum levels of α-ketoglutarate than 2‐month‐old mice. Oral supplementation restores blood levels of α-ketoglutarate in these mice.
Ireland, as of 2016, was the second-biggest per capita consumer of tea in the world, after Turkey. Local blends are the most common in Ireland, including Irish breakfast tea, using Rwandan, Kenyan and Assam teas. The annual national average of tea consumption in Ireland is 2.7 kg to 4 kg per person. Tea in Ireland is usually taken with milk or sugar and brewed longer for a stronger taste. Turkish tea is an important part of that country's cuisine and is the most commonly consumed hot drink, despite the country's long history with coffee. In 2004, Turkey produced 205,500 tonnes of tea (6.4% of the global total), which made it one of the largest tea markets in the world, with 120,000 tons being consumed in Turkey and the rest being exported. In 2010, Turkey had the highest per capita consumption in the world at 2.7 kg. As of 2013, the per-capita consumption of Turkish tea exceeds 10 cups per day and 13.8 kg per year. Tea is grown mostly in Rize Province on the Black Sea coast.
Sources: en.wikipedia.org
It is a synthetic five-amino-acid peptide that acts as a growth hormone secretagogue. Three of its residues are non-standard amino acids, and the chain ends in an amide rather than a free acid. The molecule is small enough that it can be characterised by routine peptide analytical techniques.
It has not received marketing approval as a medicine in the United States or the European Union. Supplied material is generally described and handled as a research chemical. Regulatory treatment varies by jurisdiction, and some countries restrict growth hormone secretagogues under sports or medicines legislation.
Earlier secretagogues were associated with broader hormonal responses, including measurable changes in cortisol and prolactin. Reports on this peptide describe a narrower profile in which growth hormone release is the most prominent effect. The observation is influential because it shapes how the compound is compared with other members of the same receptor family.
不是。它属于人工合成的五肽，设计上模拟胃饥饿素受体的部分作用，但不存在于人体天然激素谱中。