A practical reference on melanocortin receptor: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-05-19. Anything still debated is marked as such rather than presented as settled.
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.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
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.
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.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
| 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 |
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous tridecapeptide that regulates pigment production. Two modifications distinguish it from the natural hormone: norleucine replaces methionine at the N-terminus, which limits oxidation, and a D-phenylalanine substitution raises receptor affinity. The ring is closed through an aspartate-lysine lactam bridge, giving the molecule a constrained conformation. The free base has a molecular mass near 1024 daltons, and commercial material is usually supplied as an acetate salt. It appears in the literature as a research peptide rather than an approved therapeutic agent.
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
In business and investing, a megacap stock (also mega-cap or mega cap) is a stock whose market capitalization (market cap) is among the very largest. These are stocks of the largest publicly traded companies in the world. The market capitalization of a stock is the total value of the shares outstanding, calculated as (shares outstanding x share price). Stocks with large market caps, but smaller than megacaps, instead fall within the large-cap segment of the stock market. There is no official definition of, or full consensus agreement about, the exact market cap cutoff value for a stock to qualify as megacap, and it may vary internationally. However, for the 2020s US market, a minimum market cap value of $200 billion is often cited. Index providers, investment funds, and investment managers may have other definitions.
Cu2+ + 2 e− → Cu (cathode), E°cell = 0.34 V Copper sulfate is commonly included in teenage chemistry sets and undergraduate experiments. It is often used to grow crystals in schools and in Copper electroplating experiments despite its toxicity. Copper sulfate is often used to demonstrate an exothermic reaction, in which steel wool or magnesium ribbon is placed in an aqueous solution of CuSO4. It is used to demonstrate the principle of mineral hydration. The pentahydrate form, which is blue, is heated, turning the copper sulfate into the anhydrous form which is white, while the water that was present in the pentahydrate form evaporates. When water is then added to the anhydrous compound, it turns back into the pentahydrate form, regaining its blue color. Copper(II) sulfate pentahydrate can easily be produced by crystallization from solution as copper(II) sulfate, which is hygroscopic.
=== The glutamate family of amino acids === The glutamate family of amino acids includes the amino acids that derive from the amino acid glutamate. This family includes: glutamate, glutamine, proline, and arginine. This family also includes the amino acid lysine, which is derived from α-ketoglutarate. The biosynthesis of glutamate and glutamine is a key step in the nitrogen assimilation discussed above. The enzymes GOGAT and GDH catalyze the nitrogen assimilation reactions. In bacteria, the enzyme glutamate 5-kinase initiates the biosynthesis of proline by transferring a phosphate group from ATP onto glutamate. The next reaction is catalyzed by the enzyme pyrroline-5-carboxylate synthase (P5CS), which catalyzes the reduction of the ϒ-carboxyl group of L-glutamate 5-phosphate. This results in the formation of glutamate semialdehyde, which spontaneously cyclizes to pyrroline-5-carboxylate. Pyrroline-5-carboxylate is further reduced by the enzyme pyrroline-5-carboxylate reductase (P5CR) to yield a proline amino acid. In the first step of arginine biosynthesis in bacteria, glutamate is acetylated by transferring the acetyl group from acetyl-CoA at the N-α position; this prevents spontaneous cyclization. The enzyme N-acetylglutamate synthase (glutamate N-acetyltransferase) is responsible for catalyzing the acetylation step. Subsequent steps are catalyzed by the enzymes N-acetylglutamate kinase, N-acetyl-gamma-glutamyl-phosphate reductase, and acetylornithine/succinyldiamino pimelate aminotransferase and yield the N-acetyl-L-ornithine.
Perhaps more serious is the introduced beech bark disease complex, which includes both a scale insect (Cryptococcus fagisuga) and fungal components. During the 19th and early 20th centuries, the Appalachian forests were subject to severe and destructive logging and land clearing, which resulted in the designation of the national forests and parks as well many state-protected areas. However, these and a variety of other destructive activities continue, albeit in diminished forms; and thus far only a few ecologically based management practices have taken hold. Appalachian bogs are boreal ecosystems, which occur in many places in the Appalachians, particularly the Allegheny and Blue Ridge subranges. Though popularly called bogs, many of them are technically fens. Several mountain summits in the southern Appalachians are covered with expansive open habitats (either grassy meadows or heath) known as Appalachian balds. These habitats support many unique plant and animal communities, including rare, relict species, that are adapted to the open, exposed habitat. Their origins are heavily debated; while all were formerly thought to have anthropogenic origins, more recent evidence indicates a mixed origin: many were formed by climatic conditions in the Pleistocene and kept open by Pleistocene megafauna, then by other grazing wildlife (such as bison, elk, and deer) and Native American burning practices, and finally by grazing livestock introduced by European settlers. Others, especially those dominated by introduced grasses, may be fully anthropogenic in origin.
Like ethylene glycol and propylene glycol, glycerol is a non-ionic kosmotrope that forms strong hydrogen bonds with water molecules, competing with water-water hydrogen bonds. This interaction disrupts the formation of ice. The minimum freezing point temperature is about −38 °C (−36 °F) corresponding to 70% glycerol in water. Glycerol was historically used as an anti-freeze for automotive applications before being replaced by ethylene glycol, which has a lower freezing point. While the minimum freezing point of a glycerol-water mixture is higher than an ethylene glycol-water mixture, glycerol is not toxic and is being re-examined for use in automotive applications. In the laboratory, glycerol is a common component of solvents for enzymatic reagents stored at temperatures below 0 °C (32 °F) due to the depression of the freezing temperature. It is also used as a cryoprotectant where the glycerol is dissolved in water to reduce damage by ice crystals to laboratory organisms that are stored in frozen solutions, such as fungi, bacteria, nematodes, and mammalian embryos. Some organisms like the moor frog produce glycerol to survive freezing temperatures during hibernation.
Sources: en.wikipedia.org
== Selected publications == Kiessling, Laura L.; Pohl, Nicola L. (1996-02-01). "Strength in numbers: non-natural polyvalent carbohydrate derivatives". Chemistry & Biology. 3 (2): 71–77. doi:10.1016/S1074-5521(96)90280-X. ISSN 1074-5521. PMID 8807830. Ko, Kwang-Seuk; Jaipuri, Firoz A.; Pohl, Nicola L. (2005-09-28). "Fluorous-Based Carbohydrate Microarrays". Journal of the American Chemical Society. 127 (38): 13162–13163. Bibcode:2005JAChS.12713162K. doi:10.1021/ja054811k. ISSN 0002-7863. PMID 16173741. Wacker, Michael; Feldman, Mario F.; Callewaert, Nico; Kowarik, Michael; Clarke, Bradley R.; Pohl, Nicola L.; Hernandez, Marcela; Vines, Enrique D.; Valvano, Miguel A.; Whitfield, Chris; Aebi, Markus (2006-05-02). "Substrate specificity of bacterial oligosaccharyltransferase suggests a common transfer mechanism for the bacterial and eukaryotic systems". Proceedings of the National Academy of Sciences. 103 (18): 7088–7093. Bibcode:2006PNAS..103.7088W. doi:10.1073/pnas.0509207103. ISSN 0027-8424. PMC 1459022. PMID 16641107.
=== Bill Adler === Bill Adler (Trevor White) is the global head of FICC (Fixed Income, Currencies and Commodities) at Pierpoint, and is based out of the New York headquarters. Adler is a ruthless pragmatist fiercely devoted to the firm; he is also a longtime friend of Eric, who initially hired him, but as his senior, he is shown to feel entitled to Eric's loyalty and support. Adler first appears in the series 1 finale to vet new grads on the RIF day. He makes Harper a deal to reinstate Eric after she got him fired for his verbal abuse in the workplace. In series 2, Eric visits Adler in New York following the loss of Felim Bichan as a client and confronts him over reduced compensation for his team and the rumored consolidation of the London and New York desks. Adler rebuffs Eric, citing his underperformance, and sidelines him in a non-trading role. DVD later goes to Adler to report client Nicole Craig's sexual assault of new hire Venetia Berens, but Adler tells him to bury the case. When Harper and Eric go to Adler proposing a leaner London office and threaten to publicize Pierpoint's culture of suppression, Adler accepts their terms, consolidating CPS and FX and allowing DVD to be dismissed. In series 3, Adler supports Eric’s promotion to partner but orders him to fire a trader to demonstrate authority, leading Eric to dismiss Kenny Kilbane. Adler intervenes directly on the trading floor during the Lumi IPO to reassure investors.
=== Size === Bottles tend to come in standard sizes, often 4 US fluid ounces (120 ml) and 8 US fluid ounces (240 ml). Smaller bottles may be lighter and easier to hold and are often used with younger, smaller infants. There are concerns that larger bottles may lead to over-feeding, since parents are likely to encourage a baby to "finish" a bottle during a feeding. The height-to-width ratio of bottles is high (relative to adult cups) because it is needed to ensure the contents flood the teat when used at normal angles; otherwise the baby will drink air. However, if the bottle is too tall, it easily tips. There are asymmetric bottles that ensure the contents flood the teat if the bottle is held at a certain direction.
Myxedema coma is an extreme or decompensated form of hypothyroidism and, while uncommon, is potentially lethal. A person may have laboratory values identical to a "normal" hypothyroid state, but a stressful event (such as an infection, myocardial infarction, or stroke) precipitates the myxedema coma state, usually in the elderly. Primary symptoms of myxedema coma are altered mental status and low body temperature. Low blood sugar, low blood pressure, hyponatremia, hypercapnia, hypoxia, slowed heart rate, and hypoventilation may also occur. Myxedema, although included in the name, is not necessarily seen in myxedema coma. Coma is also not necessarily seen in myxedema coma, as patients may be obtunded without being comatose. According to newer theories, myxedema coma could result from allostatic overload in a situation where the effects of hypothyroidism are amplified by nonthyroidal illness syndrome.
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.
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.