If you have been reading about electrospray ionisation 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 2025-11-12. Numbers and descriptions here follow the published literature rather than marketing material.
Ipamorelin is a synthetic pentapeptide first described in the 1990s by researchers at Novo Nordisk during a program to develop selective growth hormone secretagogues. Its sequence is Aib-His-D-2-Nal-D-Phe-Lys-NH2, incorporating two non-natural residues, alpha-aminoisobutyric acid and D-2-naphthylalanine. The C-terminus is amidated, and the material is supplied as a white lyophilized powder. The molecular formula is C38H49N9O5 and the monoisotopic mass is approximately 711.85 daltons. The short chain and modified residues give it greater resistance to enzymatic degradation than many larger peptide hormones.
At the molecular level, ipamorelin acts as an agonist at the growth hormone secretagogue receptor type 1a, the same G protein-coupled receptor that binds ghrelin. Receptor activation couples to Gq/11 signaling, raising intracellular calcium through inositol trisphosphate and diacylglycerol, which in turn promotes exocytosis of growth hormone from pituitary somatotroph cells. Ipamorelin binds this receptor with high affinity and shows weak activity at other secretagogue-related targets in vitro. Its action requires the intact receptor and is not reversed by growth hormone-releasing hormone antagonists.
Compared with earlier growth hormone secretagogues such as GHRP-6 and hexarelin, ipamorelin has been reported to produce less stimulation of adrenocorticotropic hormone, cortisol, and prolactin in animal and early human studies. This selectivity is usually attributed to differences in receptor subtype interactions and to the tissue distribution of the receptor. Effects on appetite appear weaker than those of ghrelin itself, although the supporting evidence base is small. Whether these differences produce a distinct clinical profile remains an open question, since controlled human trials are limited.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C38H49N9O5 | Pentapeptide with amidated C-terminus |
| Molecular weight | 711.85 g/mol | Monoisotopic mass |
| Primary receptor | GHS-R1a | Ghrelin receptor, Gq/11 coupled |
| Peptide class | Synthetic pentapeptide | Contains two non-natural residues |
| Reported selectivity | Lower cortisol and prolactin effect | Observed in animal and early human work |
Material supplied for research use is normally a white to off-white lyophilized powder. The solid is hygroscopic and is handled in a low-humidity environment to limit water uptake. Bulk quantities are frequently shipped in sealed vials under inert gas. Once reconstituted in water or a neutral buffer, the solution is less stable than the dry powder and is usually divided into single-use aliquots.
Long-term storage of the dry powder is typically at minus twenty degrees Celsius or lower, protected from light and moisture. Solutions are commonly kept frozen and thawed only once, because repeated freeze-thaw cycles can promote aggregation and loss of measurable peptide content. Buffers near neutral pH are preferred over strongly acidic or strongly basic conditions. Shipping at ambient temperature is acceptable for short periods when the powder remains sealed and desiccated.
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.
Ipamorelin is a synthetic pentapeptide that belongs to the growth hormone secretagogue class of compounds. Researchers at a pharmaceutical company first described it in the 1990s while screening small peptides for growth hormone releasing activity. Its chain contains five amino acid residues, two of which are non-natural building blocks, including 2-aminoisobutyric acid and a naphthylalanine derivative. The molecule was designed to act at the ghrelin receptor while avoiding several effects observed with earlier secretagogues.
At the cellular level, ipamorelin binds the growth hormone secretagogue receptor, also called the ghrelin receptor. Activation of this receptor on pituitary somatotroph cells triggers a signaling cascade that leads to release of growth hormone into circulation. Because release follows a pulsatile pattern, studies often report peak concentration and total area under the curve rather than a single time point. Selectivity for this receptor is the property most frequently discussed in comparative work.
Modulation of Bacillus thuringiensis phosphatidylinositolspecific phospholipase C activity by mutations in the putative dimerization interface. Journal of Biological Chemistry 284(23):15607-15618. 2009 With M. Pu, J. Feng, and M. F. Roberts. Enzymology with a spin-labeled phospholipase C: Soluble substrate binding by 31P NMR from 0.005 to 11.7 T. Biochemistry 48(35):8282–8284. With X. Shi, et al. Modulation of Bacillus thuringiensis phosphatidylinositol-specific phospholipase C activity by mutations in the putative dimerization interface. Journal of Biological Chemistry 284(23):15607–15618.
== Enzyme structure == The enzyme can be found in a monofunctional form, in some bacteria and yeast. Structural analysis of the yeast monofunctional enzyme indicates that the enzyme is a dimer composed of three distinct regions; an N-terminal nucleotide-binding domain, a short central dimerisation region, and a C-terminal catalytic domain. The N-terminal domain forms a modified Rossmann fold, while the catalytic domain forms a novel alpha-beta mixed sheet. The enzyme can also be found in a bifunctional form consisting of an N-terminal aspartokinase domain and a C-terminal homoserine dehydrogenase domain, as found in bacteria such as Escherichia coli and in plants. The bifunctional aspartokinase-homoserine dehydrogenase (AK-HSD) enzyme has a regulatory domain that consists of two subdomains with a common loop-alpha helix-loop-beta strand loop-beta strand motif. Each subdomain contains an ACT domain that allows for complex regulation of several different protein functions. The AK-HSD gene codes for aspartate kinase, an intermediate domain (coding for the linker region between the two enzymes in the bifunctional form), and finally the coding sequence for homoserine dehydrogenase. As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes PDB: 1EBF, PDB: 1EBU, PDB: 1Q7G, and PDB: 1TVE.
== Diagnosis == Because of the varying symptoms of aortic dissection, the diagnosis is sometimes difficult to make. Concern should be increased in those with low blood pressure, neurological problems, and unequal pulses. The diagnosis of aortic dissection is made by visualization of the intimal flap on a diagnostic imaging test. The gold standard test is CT angiography of the aorta. Other possible tests include a CT scan of the chest, cardiac magnetic resonance (MRI), or echocardiography.
Sources: en.wikipedia.org
==== Mechanical properties ==== DBHA exhibits shear thinning behaviour and at low strains, storage and loss moduli are independent of strain but past a critical strain, the hydrogel yields and is transformed from a solid to a liquid.
=== October === 1 October – In a televised address from Downing Street, Prime Minister Sir Keir Starmer condemns Iran's missile attack on Israel and says that Britain "stand[s] with Israel and ... [recognises] her right to self-defence in the face of this aggression". 2 October – Starmer makes his first visit to Brussels as prime minister, where he is attempting to rebuild UK–EU relations. It is reported that Starmer has repaid £6,000 in gifts and hospitality received since becoming prime minister. The Parliamentary Commission on Standards has launched an investigation into Labour peer Lord Alli over allegations of failing to register interests. 3 October – The UK announces that it will give up sovereignty of the Chagos Islands to Mauritius, subject to finalisation of a treaty. BBC presenter Laura Kuenssberg cancels a scheduled televised interview with Boris Johnson after accidentally sending him her briefing notes. Labour MP Kim Leadbeater announces plans to introduce a bill on assisted dying after earlier being selected to put forward a private member's bill. 4 October – GB News loses a High Court challenge against Ofcom in which it hoped to temporarily block the regulator from sanctioning it over its People's Forum programme featuring Rishi Sunak in February, while Sunak was prime minister. GB News is given permission to challenge the ruling, with Ofcom agreeing to hold off publication of its findings until the case is heard.
2-, alpha-, or α-amino acids have the generic formula H2NCHRCOOH in most cases, where R is an organic substituent known as a "side chain". Of the many hundreds of described amino acids, 22 are proteinogenic ("protein-building"). It is these 22 compounds that combine to give a vast array of peptides and proteins assembled by ribosomes. Non-proteinogenic amino acids may arise through nonribosomal peptide synthesis. Modified amino acids, by contrast, typically result from post-translational modification. Amino acids with the structure NH+3−CXY−CXY−CO−2, such as β-alanine, a component of carnosine and a few other peptides, are β-amino acids. Ones with the structure NH+3−CXY−CXY−CXY−CO−2 are γ-amino acids, and so on, where X and Y are two substituents (one of which is normally H).
Sources: en.wikipedia.org
It is a synthetic pentapeptide belonging to the growth hormone secretagogue family. Its principal characterized target is the ghrelin receptor, also called GHS-R1a. The molecule contains non-natural amino acids and an amidated C-terminus.
Both act at the same G protein-coupled receptor, but ipamorelin is a short synthetic peptide with modified residues rather than the natural 28-amino-acid hormone. Reports describe weaker effects on appetite and on cortisol or prolactin release than those seen with ghrelin. Its resistance to enzymatic breakdown also differs from that of the natural ligand.
Receptor binding and downstream calcium signaling are well characterized in cell-based systems. Effects measured in whole organisms are less consistent across studies and species. The extent to which selective receptor behavior drives the observed hormonal profile is still debated.
Results are most often expressed as a percentage of total peak area from a reversed-phase separation. That figure reflects the detection wavelength, gradient and integration choices used by the laboratory. Two valid certificates can therefore quote different values for the same material without either being incorrect.