If you have been reading about RP-HPLC and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
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。
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 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.
| 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 |
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.
Structural features distinguish the molecule from earlier secretagogues. An alpha-aminoisobutyric acid residue near the N-terminus and a D-naphthylalanine substitution increase receptor affinity, while C-terminal amidation improves resistance to exopeptidases. These modifications are associated with reduced stimulation of appetite and of the hypothalamic-pituitary-adrenal axis compared with hexarelin or growth hormone releasing peptide-6. Whether the same profile applies at every dose level studied is a matter of ongoing investigation rather than settled consensus.
Lyophilized ipamorelin is generally held at minus twenty degrees Celsius or colder, protected from light and moisture. In solution the peptide is less stable, and degradation proceeds through hydrolysis of the amide backbone, oxidation of the histidine residue, and aggregation. Repeated freeze-thaw cycles accelerate these processes, so dividing material into single-use aliquots before freezing is common practice in research settings. Buffered formulations near neutral pH tend to show the slowest degradation, while strongly acidic or basic conditions raise hydrolysis rates. Stability data specific to ipamorelin are sparse, and much guidance is extrapolated from other short peptides.
Quality control for research-grade ipamorelin is not governed by a single harmonized pharmacopeial monograph, so certificates of analysis vary between suppliers. Common tests include appearance, solubility, water content, peptide content by quantitative amino acid analysis, and residual counterion measurement. Independent verification by an outside laboratory is often used to confirm identity and purity claims. Salt form, counterion content, and residual solvent levels are frequently unspecified, which complicates direct comparison between lots and leaves reproducibility partly unresolved.
Identity and purity assessment of ipamorelin relies mainly on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometers, a wavelength where the peptide backbone absorbs. Mass confirmation is typically obtained by electrospray ionization mass spectrometry or by liquid chromatography coupled to mass spectrometry, comparing the observed mass with the calculated value. Amino acid analysis and peptide mapping after enzymatic digestion can confirm the sequence. Impurity profiles include deletion peptides, truncated fragments, and oxidation products, reported as relative area percentages.
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.
Reversed-phase high-performance liquid chromatography is the standard method for purity assessment, most often on a C18 column with a water and acetonitrile gradient and trifluoroacetic acid or formic acid as an ion-pairing agent. Mass spectrometry by electrospray or matrix-assisted laser desorption confirms the expected mass and reveals truncated or modified sequences. Amino acid analysis and sequencing provide orthogonal structural evidence. Typical impurities include deletion sequences, oxidized products, and dimeric species. Detection wavelength, usually 214 or 220 nanometers, should be reported because response factors differ between peptides.
Purity is normally reported as a percentage of total peak area, a figure that does not account for water content, residual solvents, or counterions. Trifluoroacetate and acetate are the most frequent counterions in lyophilized peptides, and they shift the true peptide content away from the mass of the powder. A separate quantitative assay is therefore needed to state content accurately. Certificates of analysis often omit these details, which makes batch-to-batch comparison difficult and limits conclusions drawn when results from different suppliers are compared.
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。
9e Compagnie de Commandement et de Transmissions (9e CCT) - Command and Signals Company in Poitiers with VAB Régiment d'Infanterie-Chars de Marine (RICM) - Armoured Marine Infantry Regiment (light cavalry) in Poitiers with AMX 10 RC and ERC 90 1er Régiment d'Infanterie de Marine (1er RIMa) - Armoured Marine Infantry Regiment (light cavalry) in Angoulême with AMX 10 RC and ERC 90 2e Régiment d'Infanterie de Marine (2e RIMa) - Marine Infantry Regiment in Le Mans with VBCI 3e Régiment d'Infanterie de Marine (3e RIMa) - Marine Infantry Regiment in Vannes with VAB 126e Régiment d'Infanterie (126e RI) - Infantry Regiment in Brive-la-Gaillarde with VAB (will be the first unit to receive the new VBMR Griffon in 2018) 11e Régiment d'Artillerie de Marine (11e RAMa) - Marine Artillery Regiment in Saint-Aubin-du-Cormier with TRF1 howitzers, CAESAR self-propelled howitzers and RTF1 mortars 6e Régiment du Génie (6e RG) - Engineer Regiment in Angers
protomer Any molecular subunit from which a larger polymeric macromolecule is built, including those subunits which are not strictly monomers and can themselves be divided into subunits. For example, a heterodimer of tubulin proteins is the protomer for microtubule assembly.
Architecture The topic of the origin of Romanian culture began to be discussed by the end of the 18th century among the Transylvanian School scholars. Several writers rose to prominence in the 19th century, including: George Coșbuc, Ioan Slavici, Mihail Kogălniceanu, Vasile Alecsandri, Nicolae Bălcescu, Ion Luca Caragiale, Ion Creangă, and Mihai Eminescu, the later being considered the greatest and most influential Romanian poet, particularly for the poem Luceafărul. In the 20th century, a number of Romanian artists and writers achieved international acclaim, including: Tristan Tzara, Marcel Janco, Mircea Eliade, Nicolae Grigorescu, Marin Preda, Liviu Rebreanu, Eugène Ionesco, Emil Cioran, and Constantin Brâncuși. Brâncuși has a sculptural ensemble in Târgu Jiu, while his sculpture Bird in Space, was auctioned in 2005 for $27.5 million. Romanian-born Holocaust survivor Elie Wiesel received the Nobel Peace Prize in 1986, while Banat Swabian writer Herta Müller received the 2009 Nobel Prize in Literature.
Dickinsonia fossils are another notable fossil from the Ediacaran period, found in Southern Australia and Russia. It remains unknown what type of organism Dickinsonia was; however, it has been considered a polychaete, turbellarian/annelid worm, jellyfish, polyp, protist, lichen or mushroom. They were preserved in quartz sandstones, and date back to around 550 million years ago. Dickinsonia were soft-bodied organisms, that show some evidence of very slow movement. There are faint, circular imprints in the rock which follow a path, and then following the same path there is a more definite circular imprint of the same size. This indicates that the organism probably moved slowly from one feeding area to the next and absorbed nutrients. It is speculated that the organism probably had very small appendages that allowed it to move much like starfish do today.
Sources: en.wikipedia.org
== Methods == Amino acid racemization analysis consists of sample preparation, isolating the amino acid wanted, and measuring its D:L ratio. Sample preparation entails the identification, raw extraction, and separation of proteins into their constituent amino acids, typically by grinding the sample followed by acid hydrolysis. The amino acid derivative hydrolysis product can be combined with a chiral specific fluorescent, separated by chromatography or electrophoresis, and the particular amino acid D:L ratio determined by fluorescence. Alternatively, the particular amino acid can be separated by chromatography or electrophoresis, combined with a metal cation, and the D:L ratio determined by mass spectrometry. Conventional racemization analysis tends to report a D-alloisoleucine / L-isoleucine ratio (A/I or D/L ratio). This stereoisomer pair has the advantages of being relatively easy to measure and being chronologically useful through the Quaternary. Reversed phase HPLC techniques can measure up to 9 amino acids useful in geochronology over different time scales on a single chromatogram (aspartic acid, glutamic acid, serine, alanine, arginine, tyrosine, valine, phenylalanine, leucine). Amino acid dating relies on the assumption that the fraction of amino acids being studied has been a closed system since its formation, exchanging nothing with its surroundings. Removing amino acids that have diffused into the sample from its surroundings decreases variability in results by ensuring that analysis is performed only on the most representative fraction of amino acids.
=== Role of eRF3 === There have been many hypotheses on the function of eRF3 in the termination complex. An early hypothesis was that eRF3 helped eRF1 bind to the stop codon since eRF3 was structurally similar to EF-TU, which is a GTPase that brings charged tRNA molecules to the aminoacyl site of the ribosome in prokaryotic cells. Other hypothesis focus on the effects of GTP hydrolysis, which is mediated by eRF3, on eRF1. The pre-hydrolyzed GTP configuration of the termination complex favors eRF1 binding to the stop codon and orientating eRF1 to the peptide tRNA. The post-hydrolyzed GDP configuration promotes the release of the complex and dissociation of the ribosome. Additional studies hypothesis that the hydrolysis of GTP due to eRF3 allows the catalytic site of eRF1 to enter the p-site of the ribosome thus promoting the release of the nascent polypeptide.
A mass spectrometer consists of 5 components: sample inlet, ion source (or ionizer), mass analyzer, detector, data system. Each component can be varied somewhat independently from the other components, and the full mass spectrometer itself can be included as a component in an analysis pipeline, allowing great flexibility. The sample inlet prepares the sample to be analyzed in a suitable state. The ion source takes samples from the sample inlet, converts a portion of the sample into a stream of ions, and outputs it to the mass analyzer. There is a wide variety of ionization techniques, depending on the phase (solid, liquid, gas) of the sample and the efficiency of various ionization mechanisms for the unknown species. An extraction system removes ions from the sample, which are then targeted into the mass analyzer. The mass analyzer takes an input stream of ions and separates ("analyzes") its constituent ions according to their m/z, the mass-to-charge ratio. The detector measures the value of an indicator quantity and thus provides data for calculating the abundances of each ion present. Some detectors also give spatial information, e.g., a multichannel plate.
Sources: en.wikipedia.org
The rate of proteolysis may also depend on the physiological state of the organism, such as its hormonal state as well as nutritional status. In time of starvation, the rate of protein degradation increases.
Although the mechanism of this reaction has not been fully elucidated, it is speculated that the use of an electron-deficient phosphonate accelerates elimination of the oxaphosphatane intermediate. This renders the initial addition of the phosphonate-stabilized carbanion to the aldehyde effectively irreversible, leading to Z-selectivity in analogy to the standard Wittig reaction.
For services to the community in Riseley, Bedfordshire. Christine Mary Gendall. For services to the community in Penzance, Cornwall. Terence Brian Gerry. For services to the community in Plymouth, Devon. Beth Laura Gevell. Co-Founder and Director, Arts for Life Project (UK). For services to Young People and to Charity. Amanda Elizabeth Giddins. Chair, Giddo's Gift. For voluntary and charitable services to Young People with Cancer. Kenneth Matthew Gillespie. For services to Young People through Scouting. James Bruce Gillett. For services to the community in Charvil and Reading, Berkshire. Janet Elizabeth Gloin. Manager and Coach, Women's Football, Orpington Football Club. For services to Association Football and to the community in the London Borough of Bromley. Geoffery Frederick Bewick Goldsbrough. Founder, Perennials Charity Rugby Club. For services to Charity in Northern Ireland. Sarah Louise Goodall. Watch Manager, West Yorkshire Fire and Rescue Service. For services to Fire and Rescue. Susan Joy Graham. Chair, Age UK Milton Keynes. For services to Older People in Milton Keynes and Buckinghamshire. Marc Anthony Grayston. Chief Instructor, Maru Karate Kai. For services to Disadvantaged Young People and to the community in Basildon, Essex. Beverley Michelle Greenwood. For services to the community in Glenfield, Leicestershire during Covid-19. Rachael Greenwood. For services to the community in Bramdean and Hinton Ampner, Hampshire. Richard Gregory. For services to the community in Basildon, Essex. Harbaksh Singh Grewal. Vice Chair, UK Punjab Heritage Association.
== Initiatives == In 2022 ASCP received a multi-year grant over $1M to promote the CDC OneLab initiative, a network of laboratory professionals and testers to support rapid, large-scale responses to public health emergencies.
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。