Everything below concerns afamelanotide. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-01-13. Numbers and descriptions here follow the published literature rather than marketing material.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
Regulatory status differs by country, and in many places supplying the compound for human consumption is unlawful. Vendors frequently label material as intended for research use only, a designation that shifts stated purpose but does not create a legal pathway for personal use. Certificates of analysis accompanying such products vary widely in detail and provenance. Third-party testing exists but is voluntary, and results are rarely linked to a specific lot in a publicly verifiable way.
Identity testing for a synthetic peptide relies on several complementary methods. Reversed-phase high-performance liquid chromatography separates the target from related impurities and reports purity as a percentage of total peak area. Mass spectrometry confirms molecular mass and can reveal deletions or truncations. Amino acid analysis and peptide mapping provide sequence-level confirmation, while counter-ion content and residual solvents are measured separately. A purity figure alone does not establish identity, so a complete dataset combines chromatographic and spectrometric evidence.
Lyophilized peptide powder is generally stored frozen, protected from light and moisture. Tryptophan residues are susceptible to oxidation, and the lactam bridge can hydrolyze under strongly acidic or basic conditions. Solutions prepared for laboratory work degrade faster than dry powder, and repeated freeze-thaw cycles accelerate loss. Common practice is to aliquot solutions before freezing and to avoid alkaline buffers. Reported stability windows vary with concentration, buffer, and temperature, so exact shelf lives are method-specific rather than universal.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Cyclic heptapeptide, C-terminally amidated |
| Approximate molecular mass | 1024 Da | Monoisotopic mass of the free peptide |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility class | Soluble in water and polar solvents | Also dissolves in neutral aqueous buffer |
| Common synonyms | Melanotan II, MT-II, MT-2 | Described as a melanocortin agonist in early literature |
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
Regulatory treatment varies by country. In the United States, melanotan-2 is not approved for any indication, and products marketed for human use fall outside the approved drug framework. Some other jurisdictions have placed it under prescription controls or listed it as a prohibited or restricted substance. Online listings frequently describe the material as a research chemical, a category that does not carry the same manufacturing and labelling requirements as approved medicines.
Solid peptide material is generally stable when kept cold and dry. Common practice is storage at -20 degrees Celsius or lower, with desiccant and protection from light. Repeated freeze-thaw cycles and exposure to moisture are associated with degradation, aggregation, or loss of material. Once dissolved, stability depends on solvent, concentration, and temperature, and solutions are usually treated as short-lived unless stability data support longer periods. Handling notes typically emphasise minimising time at ambient temperature.
As part of Operation Unified Response, the 2d BCT, on rotation as the division's Global Response Force, was alerted and deployed forces to Haiti later that same day for the mission to provide humanitarian assistance following the devastating earthquake in Haiti. Paratroopers distributed water and food during the 2010 Haiti earthquake relief. Just two months following redeployment from Haiti in 2010, elements of 2d BCT (Red Falcons) deployed to Afghanistan in support of Operation Enduring Freedom to serve as trainers for the Afghan National Security Forces. In October 2011, the Division Headquarters returned to Afghanistan, where they relieved the 10th Mountain Division as the Headquarters of Regional Command-South. In February 2012, 4th BCT deployed to Kandahar province. Taliban commander Mullah Dadullah, formed an overwhelming force in Kandahar. Zhari district in southern Kandahar is where Dadullah was recruiting a high number of jihadists. 4th BCT of the 82nd held the 5-month siege from March 2012 to the end of July, witnessing some of the most intense combat since the initial deployments since 2001, 4th BCT inflicted massive casualties among the Taliban. Performing with an almost perfect strategic plan, 4th BCT drove Dadullah and his men out of Kandahar to the Northeastern province of Kunar, where Dadullah was killed by airstrikes. As of April 2012, the 1st BCT was deployed to Afghanistan, operating in Ghazni Province, Regional Command-East.
As the wood tiger moth has populations over a large range of latitudes, it has been observed that more northern populations showed higher rates of melanization. In both yellow and white male phenotypes of the wood tiger moth, individuals with more melanin had a heightened ability to trap heat but an increased predation rate due to a weaker and less effective aposematic signal. Melanin may protect Drosophila flies and mice against DNA damage from non-UV radiation.
== Examples of target peptides == The following content uses protein primary structure single-letter location. A "[n]" prefix indicates the N-terminus and a "[c]" suffix indicates the C-terminus; sequences lacking either are found in the middle of the protein.
In the early 1960s, Mahathir visited Japan and witnessed its remarkable recovery from the devastation of Hiroshima and Nagasaki, symbolized by the 1964 Tokyo Olympics. Mahathir announced a "Look East" policy in December 1981. Under "Look East", Mahathir particularly prioritised relations with Japan, hoping this would bolster Malaysia's economy and that Japanese work ethic, values and moral norms would have a positive influence on Malaysians. He made over 100 visits to Japan. Consistent with the "Look East" strategy adopted under his leadership, there was a major push for heavy industries by Malaysia in the early 1980s.
When cannabis is cultivated for its psychoactive or medicinal properties, male plants will often be separated from females. This prevents fertilization of the female plants, either to facilitate sin semilla flowering or to provide more control over which male is chosen. Pollen produced by the male is caught and stored until it is needed. When a male plant of one strain pollinates a female of another strain, the seeds will be F1 hybrids of the male and female. These offspring will not be identical to their parents. Instead, they will have characteristics of both parents. Repeated breeding results in certain characteristics appearing with greater regularity. It is impossible for a hermaphrodite to create any male-only seeds. A hermaphrodite may create female only seeds and hermaphrodite seeds. Also the female-only seeds may carry the hermaphrodite trait. Hybridization is the process of plants and animals breeding. Natural wind currents help speed up this hybridization process and promotes a positive growth. Some plants produce many seeds while some produce little to none depending on how it is bred. If seeds are produced traits from both the original parents will be expressed. Techniques such as mutation breeding are used to develop new strains using irradiation or chemical mutagens such as colchicine. Various companies have been experimenting with creating new strains using genetic engineering techniques.
Sources: en.wikipedia.org
=== Glutaminolysis and transamination === Aside from the citric acid cycle, α-ketoglutarate is made by glutaminolysis in which the enzyme glutaminase removes the amino group from glutamine to form glutamate which is converted to α-ketoglutarate by any one of three enzymes, glutamate dehydrogenase, alanine transaminase, or aspartate transaminase (see The glutaminolytic pathways). It is also made through the action of pyridoxal phosphate-dependent enzymes (alanine transaminase) in which glutamate is converted to α-Ketoglutarate by "donating" its −NH2 to other compounds (see transamination). These reactions are reversible. In the reverse direction of these reactions, α-ketoglutarate contributes to the production of amino acids such as glutamine, proline, arginine, and lysine as well as the lowering of cellular carbon and nitrogen (i.e., N) levels; this prevents excessive levels of these two potentially toxic elements from accumulating in cells and tissues. The neurotoxin, ammonia (i.e., NH3), is also prevented from accumulating in tissues. In this metabolic pathway the −NH2 group on an amino acid is transferred to α-ketoglutarate; this forms the α-keto acid of the original amino acid and the amine-containing product of α-ketoglutarate, glutamate. The cellular glutamate passes into the circulation and is taken up by the liver where it delivers its acquired −NH2 group to the urea cycle. In effect, the latter pathway removes excess ammonia from the body in the form of urinary urea.
1993/3140) New Possibilities National Health Service Trust Dissolution Order 1993 (S.I. 1993/3141) Combined Probation Areas (Kent) Order 1993 (S.I. 1993/3142) Cayman Islands (Constitution) (Amendment) Order 1993 (S.I. 1993/3143) Child Abduction and Custody (Parties to Conventions) Order 1993 (S.I. 1993/3144) Hong Kong (Legislative Powers) (Amendment) Order 1993 (S.I. 1993/3145) Criminal Justice (Confiscation) (Northern Ireland) Order 1993 (S.I. 1993/3146) Criminal Justice Act 1988 (Designated Countries and Territories) (Amendment) (No. 2) Order 1993 (S.I. 1993/3147) Criminal Justice (International Co–operation) Act 1990 (Enforcement of Overseas Forfeiture Orders) (Amendment) (No. 2) Order 1993 (S.I. 1993/3148) Environmentally Sensitive Areas (Machair of the Uists and Benbecula, Barra and Vatersay) Designation Order 1993 (S.I. 1993/3149) Environmentally Sensitive Areas (Shetland Islands) Designation Order 1993 (S.I. 1993/3150) Registration of Births, Deaths and Marriages (Fees) (Scotland) Order 1993 (S.I. 1993/3151) Marriage Fees (Scotland) Regulations 1993 (S.I. 1993/3152) Registration of Births, Deaths, Marriages and Divorces (Fees) (Scotland) Regulations 1993 (S.I. 1993/3153) Maximum Number of Judges (Scotland) Order 1993 (S.I. 1993/3154) Criminal Justice (International Co-operation) Act 1990 (Enforcement of Overseas Forfeiture Orders) (Scotland) Amendment (No.2) Order 1993 (S.I. 1993/3155) Confiscation of the Proceeds of Drug Trafficking (Designated Countries and Territories) (Scotland) Amendment (No.2) Order 1993 (S.I.
David Ezra Green (August 5, 1910 – July 8, 1983) was an American biochemist who made significant contributions to the study of enzymes, particularly the electron transport chain and oxidative phosphorylation.
The ribosome has three binding sites for tRNA molecules that span the space between the two ribosomal subunits: the A (aminoacyl), P (peptidyl), and E (exit) sites. In addition, the ribosome has two other sites for tRNA binding that are used during mRNA decoding or during the initiation of protein synthesis. These are the T site (named elongation factor Tu) and I site (initiation). By convention, the tRNA binding sites are denoted with the site on the small ribosomal subunit listed first and the site on the large ribosomal subunit listed second. For example, the A site is often written A/A, the P site, P/P, and the E site, E/E. The binding proteins like L27, L2, L14, L15, L16 at the A- and P- sites have been determined by affinity labeling by A. P. Czernilofsky et al. (Proc. Natl. Acad. Sci, USA, pp. 230–234, 1974). Once translation initiation is complete, the first aminoacyl tRNA is located in the P/P site, ready for the elongation cycle described below. During translation elongation, tRNA first binds to the ribosome as part of a complex with elongation factor Tu (EF-Tu) or its eukaryotic (eEF-1) or archaeal counterpart. This initial tRNA binding site is called the A/T site. In the A/T site, the A-site half resides in the small ribosomal subunit where the mRNA decoding site is located. The mRNA decoding site is where the mRNA codon is read out during translation. The T-site half resides mainly on the large ribosomal subunit where EF-Tu or eEF-1 interacts with the ribosome.
Sources: en.wikipedia.org
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.
Afamelanotide is the linear analogue [Nle4-D-Phe7]-alpha-MSH, sometimes called melanotan I, while melanotan II is cyclic and carries three further substitutions. The two are distinct molecules and are not interchangeable in analytical testing.
Binding to the four melanocortin receptor subtypes is well documented in vitro. The relative contribution of each subtype to whole-body effects in humans is far less certain.
Dry powder is usually held frozen, shielded from light, and kept away from moisture. Desiccant packaging limits hydrolysis during storage. Solutions are typically aliquoted and frozen once, because repeated thawing shortens useful life.