The short version of pentapeptide fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-02-14 and is reviewed periodically as new material appears.
从用途定位看，ipamorelin 目前主要以研究用肽的身份被讨论，未见主要药品监管机构将其批准为治疗药物。市售材料通常标注仅供研究使用，不得用于人体或诊断程序。文献中它常与生长激素促分泌素、GHS-R1a 激动剂、胃饥饿素拟似物等表述并列出现。既有研究的样本量普遍偏小，因此对其效应强度与一致性的描述应保持谨慎。
Ipamorelin 是一种合成五肽，序列为 Aib-His-D-2-Nal-D-Phe-Lys-NH2，分子式 C38H49N9O5，游离碱分子量约 711.85 g/mol。它属于生长激素促分泌素（GHS）家族，作用靶点是胃饥饿素受体 GHS-R1a。该化合物由诺和诺德的研究团队在二十世纪九十年代末报道，设计目标是提高对生长激素释放的选择性。C 端酰胺化与 N 端 Aib 残基是两个用于抵抗肽酶降解的结构特征。
在 GHS 家族中，早期肽类如 GHRP-6 与 GHRP-2 会同时促进生长激素、皮质醇与催乳素的释放，并明显增加食欲。Ipamorelin 在动物与早期人体研究中表现出对生长激素释放的相对选择性，对上述其他激素的影响较小。这种差异通常归因于受体结合模式与下游信号偏向的不同，而完整的分子解释仍有待补充。需要区分的是，选择性是研究观察中的相对程度，并非绝对界限。
杂质谱一般包含缺失序列片段、差向异构体、氧化产物以及残留溶剂或反离子，其中组氨酸与芳香残基的氧化常被重点关注。反相色谱中这类杂质往往紧邻主峰洗脱，因此方法需要足够的分离度并经过系统适用性验证。纯度百分比的解读依赖于检测波长与梯度条件，不同实验室公布的数字不宜直接横向比较。参考标准品有助于跨批次对照，但其自身赋值同样需要可追溯来源。
冻干状态下的肽通常比溶液状态更稳定，常规做法是维持 -20 °C 或更低温度、保持干燥并避开强光。复溶后的降解主要来自水解、氧化与脱酰胺，速率受 pH、缓冲液种类、离子强度与温度共同影响，碱性条件一般会加快这些反应。反复冻融会造成聚集与容器吸附损失，分装保存能降低该风险。容器材质与金属离子也可能参与氧化过程，需与操作条件一并考虑。
对 ipamorelin 的常规表征以反相高效液相色谱测定纯度，检测波长多设为 214 nm，因为肽键在该波长有较强吸收。身份确认通常借助电喷雾电离质谱或串联质谱，将实测分子量与理论值逐项比对。序列层面可用肽图分析或氨基酸分析进一步验证。这些手段组合起来，可以分别覆盖纯度、身份与序列三个不同层次的信息。
| Property | Value | Notes |
|---|---|---|
| 分子式 | C38H49N9O5 | 五肽，C 端酰胺化 |
| 分子量 | 约 711.85 g/mol | 游离碱形式 |
| 外观 | 白色至类白色冻干粉 | 研究用材料的常见形态 |
| 溶解性 | 溶于水及 DMSO 等极性溶剂 | 建议现配现用 |
| 储存温度 | -20 °C 或更低 | 干燥、避光、限制冻融次数 |
Most published work on ipamorelin comes from rodent studies and small early-phase human trials. Subcutaneous and intravenous routes have been used, while oral delivery is limited by poor absorption and rapid breakdown in the gut. The reported plasma half-life is short, on the order of two hours, and varies with species and assay method. Whether chronic use produces meaningful clinical benefit remains unresolved, and long-term safety data in humans are sparse. No major regulatory agency has approved the compound as a therapeutic drug.
Ipamorelin is a synthetic pentapeptide that belongs to the growth hormone secretagogue family. Its sequence is Aib-His-D-2-Nal-D-Phe-Lys-NH2, incorporating two non-natural residues that resist enzymatic breakdown. Researchers at Novo Nordisk described the compound in the 1990s while searching for agents that release growth hormone with fewer side effects than earlier secretagogues. The molecule acts as an agonist at the ghrelin receptor, also called GHS-R1a, which is expressed in the pituitary and in several peripheral tissues.
Quality claims for research peptides vary widely across suppliers. A certificate of analysis should list purity by chromatography, the mass found by spectrometry, and the analytical conditions used. Independent testing at a third-party laboratory is a common way to check identity and purity, because documents alone cannot confirm what is inside a vial. Purity figures describe the proportion of the target peptide among detected species, and they say nothing about biological activity or sterility.
Lyophilized ipamorelin powder is the form usually supplied for laboratory work. Kept dry, protected from light, and held at minus 20 degrees Celsius or below, it remains stable for extended periods, often measured in years. Once dissolved, the peptide degrades faster through hydrolysis, oxidation, and deamidation, so solutions are typically refrigerated and used within weeks. Repeated freeze-thaw cycles and exposure to alkaline conditions accelerate loss of the parent compound.
The molecule contains five residues, including alpha-aminoisobutyric acid, D-2-naphthylalanine, and D-phenylalanine, and it ends in a lysine amide. Non-natural and D-configured residues make the chain less susceptible to common peptidases, which helps explain its resistance to rapid breakdown. Its molecular formula is C38H49N9O5, corresponding to a free-base mass near 711.9 daltons. The C-terminal amide removes a negative charge and is a recurring feature in receptor-active peptides of this family. These structural choices are usually discussed as the basis for its selectivity profile.
Published animal and early human work describes growth hormone release that is separated from comparable rises in adrenocorticotropic hormone and cortisol. Prolactin changes are reported as small in the same studies. Selectivity is attributed to binding at the ghrelin receptor and to the downstream signaling that follows, rather than to differences in how quickly the peptide is cleared. Authors commonly label the compound selective rather than potent, because the same mass produces a smaller growth hormone response than some older secretagogues tested in parallel. Whether that profile holds across species and routes of administration remains an open question.
Human data remain limited and come mainly from small, short-term studies conducted decades ago. The peptide has not received approval as a medicine from major regulators, so current availability is largely as a research chemical. Reported effects on growth hormone pulsatility, appetite, and body composition should be read as preliminary, since few independent groups have replicated the original findings. Analytical characterization of research-grade material varies between suppliers, which complicates comparison across studies. Regulatory status also differs by country, and some jurisdictions classify it as a prescription-only or otherwise restricted item.
Lyophilized material is generally held at minus twenty degrees Celsius or lower, protected from moisture and light. Repeated excursions to room temperature cause condensation inside the vial and gradual moisture uptake, both of which shorten shelf life. Containers should be allowed to equilibrate before opening so that water does not condense on the solid. Dividing a batch into single-use aliquots reduces freeze-thaw cycling. Solid peptide handled this way is usually considered stable for months to years, while the same material in solution degrades on a much shorter timescale.
Common solvents for laboratory work include water, buffered saline, and dimethyl sulfoxide. Once dissolved, the peptide is exposed to hydrolysis and oxidation, and alkaline conditions accelerate breakdown. Low-binding plasticware and the addition of a carrier protein reduce losses to container surfaces, which can otherwise be substantial at low concentrations. Solutions are typically kept cold and used within days. Investigators working with the compound generally prepare fresh working dilutions rather than storing dilute stocks, and they avoid repeated warming of the same vial.
X-inactivation The process by which one of the two copies of the X chromosome is silenced by being irreversibly condensed into transcriptionally inactive heterochromatin in the cells of female therian mammals. A form of dosage compensation, X-inactivation prevents females from producing twice as many gene products from genes on the X chromosome as males, who only have one copy of the X chromosome. Which X chromosome is inactivated is randomly determined in the early embryo, making it possible for cell lineages with different inactive Xs to exist in the same organism.
=== Biosensing === SWCNTs have nanoscale dimensions that match the size of biological species. Due to this size compatibility and their large surface-to-volume ratio, they are sensitive to changes in their chemical environment. Through covalent and non-covalent surface functionalization, SWCNTs can be precisely tailored for selective molecular interactions with a target analyte. The SWCNT represents the transduction unit that converts the interaction into a signal change (optical or electrical). Due to continuous progress in the development of detection strategies, there are numerous examples of the use of SWCNTs as highly sensitive nanosensors (even down to the single molecule level) for a variety of important biomolecules. Examples include the detection of reactive oxygen and nitrogen species, neurotransmitters, other small molecules, lipids, proteins, sugars, DNA/RNA, enzymes as well as bacteria.
==== Familial colorectal cancer type X ==== Unlike the mutations of the 5 genes associated with DNA mismatch repair, which are associated with Lynch syndrome with hereditary nonpolyposis colorectal cancer (HNPCC) due to microsatellite instability, familial colorectal cancer (CRC) type X (FCCX) gives rise to HNPCC despite microsatellite stability. FCCX is most likely etiologically heterogeneous but RPS20 may be implicated in some cases.
=== Choice of ionization source === APCI generally suffers less ion suppression than ESI, as discussed previously. Where possible, if ion suppression is unavoidable it may be advisable to switch from ESI to APCI. If this is not possible, it may be useful to switch the ESI ionisation mode from positive to negative. Since fewer compounds are ionisable in negative ionisation mode, it is entirely possible that the ion suppressing species may be removed from the analysis. However, it should also be considered that the analyte of interest may not be ionised effectively in negative mode either, rendering this approach useless.
Sources: en.wikipedia.org
Ni(CO)4 ⇌ Ni + 4 CO This behavior is exploited in the Mond process for purifying nickel. The related nickel(0) complex bis(cyclooctadiene)nickel(0) is a useful catalyst in organonickel chemistry because the cyclooctadiene (or cod) ligands are easily displaced.
=== Traditional method === Dried and cleaned stomachs of young calves are sliced into small pieces and then put into salt water or whey, together with some vinegar or wine to lower the pH of the solution. After some time (overnight or several days), the solution is filtered. The crude rennet that remains in the filtered solution can then be used to coagulate milk. About 1 gram of this solution can normally coagulate 2 to 4 litres of milk.
=== Computational chemistry and MacroModel === In addition to his contributions to synthetic organic chemistry, Clark Still was an early pioneer in applying computational methods to the study of organic compounds. Conformational analysis was integral to Still's study of macrocyclic stereocontrol, and there was a general need for a fast and reliable computational method for predicting an organic molecule's lowest energy conformation. In order to address the problem, Still and coworkers reported a simple Monte Carlo method for searching conformational space in 1989. In this procedure, the internal coordinates for an organic molecule were varied at random, and the energy of the lowest energy conformation was determined after structure minimization. After each iteration, the minimum energy was compared to the values obtained previously in order to locate the global minimum; Still referred to this overall process as a Monte Carlo multiple-minimum search. In an effort to make molecular modeling more accessible to practicing organic chemists, Still developed the integrated software program MacroModel in 1986 in association with Columbia University. Dr. Wayne Guida, a senior postdoctoral researcher in Still's group at the time, described the development of this software package in the following way:
In 1983 Stuart Beal (and also independently Santiago Schnell and Claudio Mendoza in 1997) derived a closed form solution for the time course kinetics analysis of the Michaelis-Menten mechanism. The solution, known as the Schnell-Mendoza equation, has the form:
The periodic law may be represented in multiple ways, of which the standard periodic table is only one. Within 100 years of the appearance of Mendeleev's table in 1869, Edward G. Mazurs had collected an estimated 700 different published versions of the periodic table. Many forms retain the rectangular structure, including Charles Janet's left-step periodic table (pictured below), and the modernised form of Mendeleev's original 8-column layout that is still common in Russia. Other periodic table formats have been shaped much more exotically, such as spirals (Otto Theodor Benfey's pictured to the right), circles and triangles. Alternative periodic tables are often developed to highlight or emphasize chemical or physical properties of the elements that are not as apparent in traditional periodic tables, with different ones skewed more towards emphasizing chemistry or physics at either end. The many different forms of the periodic table have prompted the questions of whether there is an optimal or definitive form of the periodic table, and if so, what it might be. There are no current consensus answers to either question. Janet's left-step table is being increasingly discussed as a candidate for being the optimal or most fundamental form; Scerri has written in support of it, as it clarifies helium's nature as an s-block element, increases regularity by having all period lengths repeated, faithfully follows Madelung's rule by making each period correspond to one value of n + ℓ, and regularises atomic number triads and the first-row anomaly trend.
Sources: en.wikipedia.org
Porous silicon (abbreviated as "PS" or "pSi") is a form of the chemical element silicon that has introduced nanopores in its microstructure, rendering a large surface to volume ratio in the order of 500 m2/cm3.
The formation of the ring system involves first alkylation of the anion from thiophenol with dimethylallyl bromide (1) to give the thioether (2). Friedel-Crafts cyclization of the olefin with the equivalent of PPA then gives the thiopyran (3). Acylation with acetyl chloride in the presence of aluminium chloride gives the methyl ketone (4). Reaction of the enolate of that ketone with diethyl chlorophosphate gives the enol phosphate 5 as a transient intermediate. This eliminates diethyl phosphite in the presence of excess base to give the corresponding acetylene 6. The anion from the reaction of the acetylene with base is then used to displace chlorine from Ethyl 6-chloronicotinate (7). This reaction affords the coupling product tazarotene (8).
== Function == The protein encoded by this gene is a noncollagenous extracellular matrix (ECM) protein. It consists of five identical glycoprotein subunits, each with EGF-like and calcium-binding (thrombospondin-like) domains. Oligomerization results from formation of a five-stranded coiled coil and disulfide bonds. Binding to other ECM proteins such as collagen appears to depend on divalent cations. Mutations can cause the osteochondrodysplasias pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED). COMP is a marker of cartilage turnover. It is present in high quantities in fibrotic scars and systemic sclerosis, and it appears to have a role in vascular wall remodeling.
Arrhenius base Any substance that, when dissolved in water, increases the concentration of OH− ions, or, alternatively, decreases the concentration of hydronium ions (H3O+), in the resulting aqueous solution. The definition is similar to that of a Brønsted–Lowry base. Contrast Arrhenius acid.
8 April A systematic review and meta-analysis published in PLOS ONE reports that regular physical activity is associated with a 25% lower risk of dementia, while prolonged sedentary behaviour (more than 8 hours of sitting per day) is associated with a 27% higher risk. Sleeping less than 7 hours or more than 8 hours per night is likewise linked to increased dementia risk. Blue Origin reports that its "Air Pioneer" reactor has extracted oxygen from melted lunar regolith simulant, yielding medical- and propellant-grade oxygen via purification of gases released during electrolysis. The system is being developed as part of the company's in situ resource utilization efforts for sustainable lunar exploration. 9 April – The first non-mammalian synapsid fossil embryo belonging to Lystrosaurus is described, confirming the hypothesis that mammal ancestors laid eggs. 13 April – A study published in the Journal of Competition Law & Economics finds that AI-driven personalised pricing could allow firms to charge different prices to individual consumers based on predicted willingness to pay, raising concerns about transparency, fairness, and potential abuse of dominant market positions under EU and UK competition law. 15 April – A study published in Science Advances finds that the Atlantic meridional overturning circulation (AMOC) is likely to weaken by 42–58% by 2100, significantly more than many previous estimates, with the most realistic climate models indicating a high probability of eventual collapse.
Sources: en.wikipedia.org
两者都是 GHS-R1a 激动剂，但 ipamorelin 在研究中显示出更高的生长激素释放选择性。早期资料显示它对皮质醇、催乳素与食欲的刺激弱于 GHRP-6。这些差异是相对程度，而非绝对区分。
公开资料中它主要以研究用肽的形式出现，未获主要监管机构批准用于治疗。可得材料通常标注仅供研究使用。任何临床用途的宣称都缺少监管依据。
序列中的 Aib 与 D-2-Nal 等非天然残基可提高对肽酶的抵抗能力，并影响受体结合的构象。这类修饰在合成肽设计中较为常见。它们也使常规氨基酸分析需要额外步骤才能确认序列。
Aib 即 α-氨基异丁酸，是一种非蛋白质源氨基酸，其侧链为两个甲基。它在肽链中倾向于诱导螺旋构象并限制骨架的柔性。这种刚性被认为有助于抵抗蛋白酶切割。