The short version of pentapeptide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-11-22. Anything still debated is marked as such rather than presented as settled.
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.
Compared with older secretagogues such as hexarelin or GHRP-6, ipamorelin shows weaker stimulation of cortisol, prolactin, and appetite in the animal models used for early characterization. Whether that selectivity is preserved across longer human exposures remains an open question, because published clinical data are limited in size and duration. Reported effects on food intake are generally described as modest. The compound is therefore treated in the literature as a relatively selective research tool rather than a fully characterized therapeutic agent.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic pentapeptide | Growth hormone secretagogue family |
| Sequence | Aib-His-D-2-Nal-D-Phe-Lys-NH2 | Contains two non-natural residues |
| Molecular formula | C38H49N9O5 | Free base form |
| Molecular weight | 711.85 g/mol | Calculated from formula |
| Primary target | GHS-R1a ghrelin receptor | Agonist activity |
Identity and purity are assessed by complementary methods rather than a single test. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and reports a percentage purity. Mass spectrometry, most often with electrospray ionization, confirms the expected molecular mass and detects sequence-related variants. Amino acid analysis can verify composition, while water content and residual counterion measurements support the mass balance of a batch. Stability studies under accelerated conditions are used to estimate shelf life, though such estimates carry uncertainty for long-term storage.
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.
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.
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.
=== Synthesis === Synthesis of RNA typically occurs in the cell nucleus and is usually catalyzed by an enzyme—RNA polymerase—using DNA as a template, a process known as transcription. Initiation of transcription begins with the binding of the enzyme to a promoter sequence in the DNA (usually found "upstream" of a gene). The DNA double helix is unwound by the helicase activity of the enzyme. The enzyme then progresses along the template strand in the 3' to 5' direction, synthesizing a complementary RNA molecule with elongation occurring in the 5' to 3' direction. The DNA sequence also dictates where termination of RNA synthesis will occur. Primary transcript RNAs are often modified by enzymes after transcription. For example, a poly(A) tail and a 5' cap are added to eukaryotic pre-mRNA and introns are removed by the spliceosome. There are also a number of RNA-dependent RNA polymerases that use RNA as their template for synthesis of a new strand of RNA. For instance, a number of RNA viruses (such as poliovirus) use this type of enzyme to replicate their genetic material. Also, RNA-dependent RNA polymerase is part of the RNA interference pathway in many organisms.
Cleavage at the reactive site results in entrapment of the thrombin protease, with movement of the cleaved reactive site loop together with the bound protease, such that the loop forms an extra sixth strand in the middle of beta sheet A. This movement of the reactive site loop can also be induced without cleavage, with the resulting crystallographic structure being identical to that of the physiologically latent conformation of plasminogen activator inhibitor-1 (PAI-1). For this reason the conformation of antithrombin in which the reactive site loop is incorporated uncleaved into the main body of the protein is referred to as latent antithrombin. In contrast to PAI-1 the transition for antithrombin from a normal or native conformation to a latent conformation is irreversible. Native antithrombin can be converted to latent antithrombin (L-antithrombin) by heating alone or heating in the presence of citrate. However, without extreme heating and at 37 °C (body temperature) 10% of all antithrombin circulating in the blood is converted to the L-antithrombin over a 24-hour period. The structure of L-antithrombin is shown in Figure 6. The 3-dimensional structure of native antithrombin was first determined in 1994. Unexpectedly the protein crystallized as a heterodimer composed of one molecule of native antithrombin and one molecule of latent antithrombin.
== Beyond plant disease == Potyvirus RNA codes for at least seven different proteins. One of them is a protease. The TEV protease is a highly site-specific protease that biochemists have used to their advantage to create a protein purification system by incorporating TEV protease's recognition site into protein purification tags. A gene construct is created containing the protein of interest fused to a TEV protease recognition site, followed by an affinity tag, such as a polyhistidine-tag. Following affinity chromatography, the purified protein is then treated with TEV protease. TEV protease cleaves at its recognition site, removing the affinity tag. This allows for affinity purification of proteins that are not well-behaved when fused to protein tags.
Another invasive neuromodulation treatment developed in the 1980s is deep brain stimulation, which may be used to help limit symptoms of movement disorder in Parkinson's disease, dystonia, or essential tremor. Deep brain stimulation was approved by the U.S. Food and Drug Administration in 1997 for essential tremor, in 2002 for Parkinson's disease, and received a humanitarian device exemption from the FDA in 2003 for motor symptoms of dystonia. It was approved in 2010 in Europe for the treatment of certain types of severe epilepsy. DBS also has shown promise, although still in research, for medically intractable psychiatric syndromes of depression, obsessive-compulsive disorders, intractable rage, dementia, and morbid obesity. It has also shown promise for Tourette syndrome, torticollis, and tardive dyskinesia. DBS therapy, unlike spinal cord stimulation, has a variety of central nervous system targets, depending on the target pathology. For Parkinson's disease, central nervous system targets include the subthalamic nucleus, globus pallidus interna, and the ventral intermidus nucleus of the thalamus. Dystonias are often treated by implants targeting globus pallidus interna, or less often, parts of the ventral thalamic group. The anterior thalamus is the target for epilepsy.
Sources: en.wikipedia.org
== Interactions == Iodine-131, a radioactive isotope used for thyroid imaging (scintigraphy) and therapy of thyroid cancers, can be less effective when used within two to six weeks after application of ioxaglic acid because of residual iodine in the body.
=== Pharmacokinetics === The bioavailability of bremelanotide with subcutaneous injection is about 100%. Following a subcutaneous injection of bremelanotide, maximal levels occur after about one hour, with a range of 0.5 to 1.0 hours. The plasma protein binding of bremelanotide is 21%. Bremelanotide is metabolized via hydrolysis of its peptide bonds. The elimination half-life of bremelanotide is 2.7 hours, with a range of 1.9 to 4.0 hours. Bremelanotide is excreted 64.8% in urine and 22.8% in feces.
immunofluorescence (IF) A family of laboratory techniques in which a particular antigen or antibody is conjugated to a fluorescent dye and then allowed to bind specifically to its complementary antibody or antigen, if any exists, in a culture vessel, tissue section or smear, hybridization probe, membrane blot, or any other context. The presence or absence of the complement and its specific location(s) can be visualized by illuminating the sample with ultraviolet light and observing the fluorescence from the conjugated fluorophore, often under a microscope.
In the case of complexes of two or more proteins, where the structures of the proteins are known or can be predicted with high accuracy, protein–protein docking methods can be used to predict the structure of the complex. Information of the effect of mutations at specific sites on the affinity of the complex helps to understand the complex structure and to guide docking methods.
=== Antibody heterogeneity === Product heterogeneity is common in monoclonal antibodies and other recombinant biological products and is typically introduced either upstream during expression or downstream during manufacturing. These variants are typically aggregates, deamidation products, glycosylation variants, oxidized amino acid side chains, as well as amino and carboxyl terminal amino acid additions. These seemingly minute structural changes can affect preclinical stability and process optimization as well as therapeutic product potency, bioavailability and immunogenicity. The generally accepted purification method of process streams for monoclonal antibodies includes capture of the product target with protein A, elution, acidification to inactivate potential mammalian viruses, followed by ion chromatography, first with anion beads and then with cation beads. Displacement chromatography has been used to identify and characterize these often unseen variants in quantities that are suitable for subsequent preclinical evaluation regimens such as animal pharmacokinetic studies. Knowledge gained during the preclinical development phase is critical for enhanced product quality understanding and provides a basis for risk management and increased regulatory flexibility. The recent Food and Drug Administration's Quality by Design initiative attempts to provide guidance on development and to facilitate design of products and processes that maximizes efficacy and safety profile while enhancing product manufacturability.
Sources: en.wikipedia.org
== Early life and education == James William Middleton was born on 15 April 1987 at the Royal Berkshire Hospital in Reading, the youngest child and only son of Michael Middleton (born 1949), a former British Airways flight dispatcher, and Carole Middleton (born 1955), a former flight attendant. His father came from a line of solicitors who lived in Leeds, West Yorkshire. His great-grandmother Olive Middleton was a member of the Lupton family, who were landed gentry. His mother's family were from County Durham. Shortly before his birth, Middleton's parents founded Party Pieces, a mail-order party supply company. His elder sisters are Catherine (born 1982) and Philippa (born 1983). The family lived in Bradfield Southend, Berkshire, before moving to the nearby village of Bucklebury in 1995. Middleton was educated at St Andrew's School, Pangbourne, and Marlborough College. In 2006, he attended the University of Edinburgh, studying environmental resources management before dropping out a year later.
==== Sweden ==== The Swedish Riksdag added 4-HO-MET to Schedule I ("substances, plant materials and fungi which normally do not have medical use") as narcotics in Sweden as of May 1, 2012, published by Medical Products Agency in their regulation LVFS 2012:6.
People with high levels of factor VIII are at increased risk for deep vein thrombosis and pulmonary embolism. Copper is a required cofactor for factor VIII and copper deficiency is known to increase the activity of factor VIII. Factor VIII is on the World Health Organization's List of Essential Medicines.
boiling point Also vaporization point. The temperature at which a substance changes state from a liquid to a gas (or vapor). It depends on pressure and is usually specified for a given substance under standard conditions.
Sources: en.wikipedia.org
It is a synthetic pentapeptide in the growth hormone secretagogue family. The chain contains five residues, two of which are non-natural amino acids.
It acts as an agonist at the growth hormone secretagogue receptor, also known as the ghrelin receptor. Binding at pituitary somatotroph cells promotes growth hormone release.
Early studies report weaker effects on cortisol, prolactin, and appetite than compounds such as GHRP-6. The size of that difference in humans is not firmly established.
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.