A practical reference on electrospray ionisation: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-06-15 and is reviewed periodically as new material appears.
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。
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。
Lyophilized material is generally stored frozen and protected from light and moisture. Typical recommendations place dry powder at temperatures well below freezing, while reconstituted solutions are kept cold and used within a defined window. Repeated freezing and thawing should be avoided because it can promote aggregation and loss of material. The choice of solvent matters as well; compatibility with the intended diluent should be checked before preparation. These handling practices aim to preserve both the quantity and the integrity of the peptide.
Verification of identity and purity relies on analytical methods used across peptide chemistry. Reverse-phase high-performance liquid chromatography separates components by hydrophobicity and provides a purity estimate. Mass spectrometry confirms molecular mass and helps detect modifications. Together these techniques give complementary information about whether a sample matches its expected structure. Results depend on method parameters and reference standards, so reported purity values are meaningful only when the analytical conditions are stated. Consistency between laboratories requires comparable protocols and well-characterized reference materials.
Peptides such as ipamorelin are subject to chemical and physical degradation. Hydrolysis of peptide bonds, oxidation of susceptible residues, and aggregation are common pathways that reduce purity over time. The rate of these processes depends on temperature, moisture, pH, and the number of freeze-thaw cycles a sample undergoes. Because the compound is typically handled as a lyophilized powder, controlling moisture during storage is a central concern. Degradation products can be detected with separation techniques that resolve the parent peptide from related impurities.
| 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 on the growth hormone secretagogue receptor, also known as the ghrelin receptor. Its sequence contains five amino acid residues, including a non-natural residue that increases stability against enzymatic breakdown. The compound was developed in the 1990s as part of research into small peptides that stimulate pituitary hormone release. Unlike larger protein hormones, it can be produced by solid-phase peptide synthesis and characterized by standard analytical methods.
At the receptor level, ipamorelin binds GHS-R1a and triggers signaling through Gq-coupled pathways. Activation leads to calcium release and downstream effects in pituitary somatotroph cells. These events promote the release of growth hormone into circulation. The response depends on the presence of the receptor and on the physiological state of the animal or tissue studied. Because the receptor is also found in other tissues, effects beyond the pituitary have been examined in laboratory models, though the extent of those effects remains an area of ongoing study.
One distinguishing feature reported in animal studies is selectivity. Ipamorelin stimulated growth hormone release with limited elevation of adrenocorticotropic hormone or cortisol compared with earlier secretagogues such as GHRP-6. This pattern has been described as more selective for the growth hormone axis. The finding comes mainly from preclinical work, and the degree to which it holds across species and doses is not fully settled. Reports also describe effects on gastric motility in animal models, suggesting activity outside the pituitary, though the clinical relevance of this observation is uncertain.
Mass spectrometry confirms identity and reveals structural deviations that chromatography alone can miss. Positive-mode electrospray ionisation generally yields multiply charged ions whose deconvoluted mass is checked against the theoretical value. Amino acid analysis, and enzymatic digestion with subsequent fragment mapping, provide independent confirmation of sequence and of the terminal amide. Analysts take care to separate the target from deletion sequences, which may differ by one residue and therefore by only a small mass increment.
The lyophilised solid is normally held at -20 °C or colder, shielded from light and moisture. Stability in that state is measured in years, although shelf life depends on residual water content and the container seal. Once dissolved, the peptide is more fragile: aqueous solutions are commonly kept at 2-8 °C and used within days to weeks, and repeated freeze-thaw cycling is avoided. Strongly acidic or basic conditions accelerate hydrolysis, and prolonged exposure to them can strip the terminal amide.
Purity assessment for this peptide relies mainly on reversed-phase high-performance liquid chromatography. A C18 column with a water-acetonitrile gradient containing trifluoroacetic acid separates the target from truncated sequences and oxidation products. Detection near 214 nm exploits the amide backbone, while the aromatic side chains allow additional monitoring close to 280 nm. Reported purity values depend on the method, so a certificate of analysis carries weight only when gradient, column and integration parameters are given.
== Early life == Geneviève Meurgues was born on 4 February 1931 in Paris, into a family originally from Saint-Germain-de-Modéon. She had sister and brother, Christiane and Bernard. Until 1962, she worked in a medical analysis laboratory while completing her education in chemistry and biochemistry at the Conservatoire national des arts et métiers. She graduated as a chemical engineer in 1967, writing her thesis on the nucleic acids of the fungus Aspergillus niger.
This is normally a "prompt" process, but sometimes does not rapidly reach to the nuclear ground state, in which case a metastable isomer has formed. This usually occurs as a spin isomer when the formation of an intermediate excited state has a spin far different from that of the ground state. Gamma-ray emission is hindered if the spin of the post-emission state differs greatly from that of the emitting state, and if the excitation energy is low; such excited states will generally have long lives and be considered metastable. After fission, several of the fission fragments may be produced in a metastable isomeric state, after their prompt de-excitation. At the end of this process, the nuclei can populate both the ground and the isomeric states. If the half-life of an isomer is long enough, it is possible to measure its production rate, and comparing it to that of the ground state gives the so-called isomeric yield ratio.
=== Given name === Reta Beebe (born 1936), American astronomer, author and popularizer of astronomy Reta Cowley (1910–2004), Canadian painter Reta Jo Lewis (born 1953), American Director of Congressional Affairs, an attorney, diplomat Reta Mays (born 1975), American serial killer Reta Shaw (1912–1982), American character actress Reta Trotman (born 1989), New Zealand racing cyclist
In 1966, Dayhoff pioneered the use of computers in comparing protein sequences and reconstructing their evolutionary histories from sequence alignments. To perform this work, she created the single-letter amino acid code to minimize the data file size for each sequence. This work, co-authored with Richard Eck, was the first application of computers to infer phylogenies from molecular sequences. It was the first reconstruction of a phylogeny (evolutionary tree) by computers from molecular sequences using a maximum parsimony method. In later years, she applied these methods to study a number of molecular relationships, such as the catalytic chain and bovine cyclic AMP-dependent protein kinase and the src gene product of Rous avian and Moloney murine sarcoma viruses; antithrombin-III, alpha-antitrypsin, and ovalbumin; epidermal growth factor and the light chain of coagulation factor X; and apolipoproteins A-I, A-II, C-I and C-III. Based on this work, Dayhoff and her coworkers developed a set of substitution matrices called the PAM (Accepted Point Mutation), MDM (Mutation Data Matrix), or Dayhoff Matrix. They are derived from global alignments of closely related protein sequences. The identification number included with the matrix (ex. PAM40, PAM100) refers to the evolutionary distance; greater numbers correspond to greater distances. Matrices using greater evolutionary distances are extrapolated from those used for lesser ones.
Sources: en.wikipedia.org
There are several geophysical methods available that can approximate in situ soil water content. These methods include: time-domain reflectometry (TDR), neutron probe, frequency domain sensor, capacitance probe, amplitude domain reflectometry, electrical resistivity tomography, ground penetrating radar (GPR), and others that are sensitive to the physical properties of water . Geophysical sensors are often used to monitor soil moisture continuously in agricultural and scientific applications.
A process in which a person is given important facts about a medical procedure or treatment, a clinical trial, or genetic testing before deciding whether or not to participate. It also includes informing the patient when there is new information that may affect his or her decision to continue. Informed consent includes information about the possible risks, benefits, and limits of the procedure, treatment, trial, or genetic testing. (NCI) The process of learning the key facts about a clinical trial before deciding whether or not to participate. It is also a continuing process throughout the study to provide information for participants. To help someone decide whether or not to participate, the doctors and nurses involved in the trial explain the details of the study. (NLM) A process by which a subject voluntarily confirms his or her willingness to participate in a particular trial, after having been informed of all aspects of the trial that are relevant to the subject's decision to participate. Informed consent is documented by means of a written, signed, and dated informed consent form. (ICH E6) Informed consent document
Prior to the 1920s in the US, the soybean was mainly a forage crop, a source of oil, meal (for feed) and industrial products, with very little used as food. However, it took on an important role after World War I. During the Great Depression, the drought-stricken (Dust Bowl) regions of the United States were able to use soy to regenerate their soil because of its nitrogen-fixing properties. Farms were increasing production to meet with government demands, and Henry Ford became a promoter of soybeans. In 1931, Ford hired chemists Robert Boyer and Frank Calvert to produce artificial silk. They succeeded in making a textile fiber of spun soy protein fibers, hardened or tanned in a formaldehyde bath, which was given the name Azlon. It never reached the commercial market. Soybean oil was used by Ford in paint for the automobiles, as well as a fluid for shock absorbers. During World War II, soybeans became important in both North America and Europe chiefly as substitutes for other protein foods and as a source of edible oil. During the war, the soybean was discovered as fertilizer due to nitrogen fixation by the United States Department of Agriculture. Prior to the 1970s, Asian-Americans and Seventh-Day Adventists were essentially the only users of soy foods in the United States.
Sources: en.wikipedia.org
Myelinated A-Fibres: The A-Fibres present in the pulp can be further classified into 2 different types. A-Delta Fibres make up 90% of the A-Fibres, while the rest are A-Beta Fibres. Have a relatively low-threshold sensory apparatus. Mainly located at the pulp-dentine border at the top of the pulp, and more specifically concentrated in the pulp horn. Have a relatively small diameter with a relatively slow conduction velocity. They are still faster than C-Fibres. A-Fibres transmit signals to the brainstem and then to the contralateral thalamus. Able to respond to stimuli through a shell of calcified tissue due to the stimulus-induced fluid flow in dentinal tubules. This is known as the hydrodynamic theory. Stimuli that displaces the fluid within the dentinal tubules will trigger the intradental myelinated A-Fibres, leading to the sharp pain sensation commonly associated with dentine hypersensitivity Unmyelinated C-Fibres: They are mainly located at the core of the pulp and extend underneath the odontoblastic layer. C-Fibres have higher pain thresholds, responsible for detecting inflammatory threats. They are heavily influenced by modulating interneurons before they reach the thalamus. C-Fibre stimulation often results in a "slow pain", normally characterised as a dull and aching pain.
== Education == High received an A.B. in chemistry at Harvard University in 1972. She started her medical training at the University of North Carolina (UNC) School of Medicine, during which she took a leave of absence to work in a chemistry research lab at UNC. After returning and completing her medical degree in 1978, High continued with a residency in internal medicine. She then became a hematology fellow at Yale University under the supervision of Edward J Benz Jr, during which she worked on the molecular genetics of globin genes and oncogenes.
Hitler, aiming to use the crisis as a pretext for war, now demanded not only the annexation of the Sudetenland but also the immediate military occupation of Bohemia, Moravia and Slovakia, thus giving the Czechoslovak army no time to adapt its defence measures to the new borders. Hitler, in a speech at the Sportpalast in Berlin, claimed that the Sudetenland was "the last territorial demand I have to make in Europe" and gave Czechoslovakia a deadline of 28 September 1938 at 2:00 p.m. to cede the Sudetenland to Germany or face war. To achieve a solution, the Italian dictator, Benito Mussolini, suggested a conference of the major powers in Munich, and on 29 September, Hitler, Daladier and Chamberlain met and agreed to Mussolini's proposal (actually prepared by Hermann Göring) and signed the Munich Agreement. They accepted the immediate occupation of the Sudetenland. The Czechoslovak government, though not party to the talks, submitted to compulsion and promised to abide by the agreement on 30 September. The Sudetenland was assigned to Germany between 1 and 10 October 1938. The Czech part of Czechoslovakia was subsequently invaded by Germany in March 1939, with a portion being annexed and the remainder turned into the Protectorate of Bohemia and Moravia. The Slovak part declared its independence from Czechoslovakia and became the Slovak Republic (Slovak State), a satellite state allied to Germany.
June 19, 1987: Law concerning the duration and organization of working time. July 22, 1987: Law on the exercise of parental authority. July 18, 1988: Creation of the Secretary of State for Women's Rights, assigned to Michèle André. December 28, 1988: Order concerning the possession, distribution, dispensing, and administration of the drug Mifepristone 200 mg tablets. May 16, 1989: Decree removing the managerial and technical staff of the prison administration's external services from the list of positions for which separate recruitment could be planned for men and women. July 10, 1989: Framework law on education. July 10, 1989: Law on the prevention of child abuse and the protection of children. February 20, 1990: Order amending the order of November 3, 1988, concerning the prices of care and hospitalization related to voluntary termination of pregnancy. July 6, 1990: Law amending the Social Security Code and relating to family benefits and employment assistance for the care of young children. September 5, 1990: Marital rape is recognized for the first time by the Court of Cassation. December 21, 1990: The Council of State validates the conformity of the 1975 Veil Law with the European Convention on Human Rights. January 18, 1991: Law containing provisions relating to public health and social insurance. January 31, 1991: Decree concerning the responsibilities of the Secretary of State for Women's Rights and Daily Life, delegated by the Minister of Labour, Employment, and Vocational Training. May 1991: Édith Cresson becomes the first female Prime Minister of France.
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。