Everything below concerns melanogenesis. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-10-12. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Routine characterisation relies on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, using a C18 column and a water-acetonitrile gradient containing trifluoroacetic acid. Electrospray ionisation mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidised by-products that co-elute poorly. Sequence and stereochemistry require additional work, such as peptide mapping or amino acid analysis, because a chromatographic purity figure alone does not distinguish a diastereomer from the target peptide. Independent testing of research-grade material frequently shows measured content below the stated label, so a certificate of analysis is best read together with the method that produced it.
Melanotan-2 is handled in the laboratory as a lyophilised powder that dissolves readily in water, dimethyl sulfoxide and dimethylformamide, with limited solubility in ethanol. Stock solutions prepared in an organic solvent often precipitate when diluted into aqueous buffer, so gradual dilution with mixing is standard practice. The peptide carries a tryptophan residue and a histidine residue, both sensitive to oxidation and to alkaline conditions. Working solutions are therefore kept near neutral to slightly acidic pH, protected from light, and consumed within the same working session whenever that is practical.
| 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 binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
Melanotan II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
Melanotan-2 appears on the World Anti-Doping Agency prohibited list within the peptide hormone class, and several national regulators treat it as an unapproved prescription substance. Some countries restrict importation or sale for personal use. Because the compound is widely traded as a research chemical, the practical legal picture differs between jurisdictions and shifts over time. Human safety data covering long periods are limited, and whether repeated pigmentation changes carry any lasting risk to melanocytes remains an open question.
Freeze-dried melanotan-2 is normally kept as a desiccated powder at minus twenty degrees Celsius or lower, shielded from light and moisture. Peptides of this size degrade through hydrolysis, oxidation and deamidation, and each pathway accelerates as temperature and water activity rise. Repeated freeze-thaw cycles promote aggregation and loss of material, so aliquoting a stock solution before freezing is standard laboratory practice. Once dissolved, the solution is markedly less stable than the powder. In laboratory work, solutions are generally refrigerated and used within days rather than kept for months.
=== Reduction === Like esters, most carboxylic acids can be reduced to alcohols by hydrogenation, or using hydride transferring agents such as lithium aluminium hydride. Strong alkyl transferring agents, such as organolithium compounds but not Grignard reagents, will reduce carboxylic acids to ketones along with transfer of the alkyl group. The Vilsmaier reagent (N,N-Dimethyl(chloromethylene)ammonium chloride; [ClHC=N+(CH3)2]Cl−) is a highly chemoselective agent for carboxylic acid reduction. It selectively activates the carboxylic acid to give the carboxymethyleneammonium salt, which can be reduced by a mild reductant like lithium tris(t-butoxy)aluminum hydride to afford an aldehyde in a one pot procedure. This procedure is known to tolerate reactive carbonyl functionalities such as ketone as well as moderately reactive ester, olefin, nitrile, and halide moieties.
Fluid mechanics is the branch of physics concerned with the mechanics of fluids (liquids, gases, and plasmas) and the forces on them. Originally applied to water (hydromechanics), it found applications in a wide range of disciplines, including mechanical, aerospace, civil, chemical, and biomedical engineering, as well as geophysics, oceanography, meteorology, astrophysics, and biology. It can be divided into fluid statics, the study of various fluids at rest; and fluid dynamics, the study of the effect of forces on fluid motion. It is a branch of continuum mechanics, a subject which models matter without using the information that it is made out of atoms; that is, it models matter from a macroscopic viewpoint rather than from microscopic. Fluid mechanics, especially fluid dynamics, is an active field of research, typically mathematically complex. Many problems are partly or wholly unsolved and are best addressed by numerical methods, typically using computers. A modern discipline, called computational fluid dynamics (CFD), is devoted to this approach. Particle image velocimetry, an experimental method for visualizing and analyzing fluid flow, also takes advantage of the highly visual nature of fluid flow.
=== 20th century === In 1924 Pacific Power installed a turbine where the canal meets the river to generate electricity. In 1984 the city bought the water system from Pacific Power, and shut down the plant in 1991. By 2003 the city had approved a plan to restart the four megawatt-hour hydroelectric plant and in February 2009 the plant opened again. Albany was the headquarters for the Mountain States Power Company from its establishment in 1918 until its merger into Pacific Power & Light (now PacifiCorp) in 1954. In the 1940s, the city started the Albany World Championship Timber Carnival, which drew competitors from all over the world to participate in logging skills contests. The event took place over the four days of the Fourth of July weekend. Men and women would compete in climbing, chopping, bucking, and burling contests. In 2001 the carnival was cancelled because of smaller crowds and the state's declining timber economy.
== Research and career == In 2007 Delibegovic returned to the United Kingdom, where she was awarded the Research Councils UK 5-year tenure track fellowship to investigate obesity and ageing at the University of Aberdeen. She was made Professor in Diabetes Physiology in 2015 at the age of 38. The field of her research has focussed on the PTP1B phosphatase, the molecular mechanisms that cause diabetes and what the relationship is between diabetes and Alzheimer's disease. She has demonstrated that PTP1B can be used for targeted treatments, reaching the cells of specific organs without causing any side effects. In 2017 Delibegovic demonstrated a novel pharmaceutical, Trodusquemine, that could be used to treat type 2 diabetes and breast cancer. She went on to show that a single dose of Trodusquemine, the PTP1B inhibitor, could be used to reverse the effects of atherosclerosis. During the COVID-19 pandemic, Delibegovic, in collaboration with an SME Vertebrate Antibodies Ltd and the NHS Grampian, obtained funding from the Scottish Government/ Chief Scientist office to develop a diagnostic test that could support mass screening for coronavirus disease. Her long-term aim was to use artificial intelligence to identify which parts of the severe acute respiratory syndrome coronavirus 2 activated the body's immune system. At the time, other coronavirus disease tests available in the United Kingdom would not support rapid deployment, and several were unreliable. In May 2020, the tests developed by Delibegovic and her team were in development.
=== Medium of instruction === At primary and secondary school levels, the government maintains a policy of "mother tongue instruction"; most schools use Cantonese as the medium of instruction, with written education in both Chinese and English. Other languages being used as the medium of instruction in non-international school education include English and Putonghua (Mandarin Chinese). Secondary schools emphasise "bi-literacy and tri-lingualism", which has encouraged the proliferation of spoken Mandarin language education. English is the official medium of instruction and assessment for most university programmes in Hong Kong, although Cantonese is predominant in informal discussions among local students and professors.
Sources: en.wikipedia.org
as a function of wavelength will yield a superposition of the effects of absorption and scattering. Because the absorption portion is more distinct and tends to ride on a background of the scatter portion, it is often used to identify and quantify the absorbing species. Consequently, this is often referred to as absorption spectroscopy, and the plotted quantity is called "absorbance", symbolized as
== Biosynthesis == Epothilone B is a 16-membered polyketide macrolactone with a methylthiazole group connected to the macrocycle by an olefinic bond. The polyketide backbone was synthesized by type I polyketide synthase (PKS) and the thiazole ring was derived from a cysteine incorporated by a nonribosomal peptide synthetase (NRPS). In this biosynthesis, both PKS and NRPS use carrier proteins, which have been post-translationally modified by phosphopantetheine groups, to join the growing chain. PKS uses coenzyme-A thioester to catalyze the reaction and modify the substrates by selectively reducing the β carbonyl to the hydroxyl (Ketoreductase, KR), the alkene (Dehydratase, DH), and the alkane (Enoyl Reductase, ER). PKS-I can also methylate the α carbon of the substrate. NRPS, on the other hand, uses amino acids activated on the enzyme as aminoacyl adenylates. Unlike PKS, epimerization, N-methylation, and heterocycle formation occurs in the NRPS enzyme.
The term "base" appears to have been first used in 1717 by the French chemist, Louis Lémery, as a synonym for the older Paracelsian term "matrix." In keeping with 16th-century animism, Paracelsus had postulated that naturally occurring salts grew within the earth as a result of a universal acid or seminal principle having impregnated an earthy matrix or womb. ... Its modern meaning and general introduction into the chemical vocabulary, however, is usually attributed to the French chemist, Guillaume-François Rouelle. ... In 1754 Rouelle explicitly defined a neutral salt as the product formed by the union of an acid with any substance, be it a water-soluble alkali, a volatile alkali, an absorbent earth, a metal, or an oil, capable of serving as "a base" for the salt "by giving it a concrete or solid form." Most acids known in the 18th century were volatile liquids or "spirits" capable of distillation, whereas salts, by their very nature, were crystalline solids. Hence it was the substance that neutralized the acid which supposedly destroyed the volatility or spirit of the acid and which imparted the property of solidity (i.e., gave a concrete base) to the resulting salt.
This was an enormous social change, doing much to increase Conservative support amongst new homeowners and which Heseltine often cites as one of his major achievements. Heseltine noted that, "no single piece of legislation has enabled the transfer of so much capital wealth from the state to the people." He said that the 'right to buy' policy had two main objectives: to give people what they had wanted, and to reverse the trend of ever-increasing dominance of the State over the life of the individual. He said: "There is in this country a deeply ingrained desire for home ownership. The Government believe that this spirit should be fostered. It reflects the wishes of the people, ensures the wide spread of wealth through society, encourages a personal desire to improve and modernize one's own home, enables parents to accrue wealth for their children and stimulates the attitudes of independence and self-reliance that are the bedrock of a free society." Many of the homes sold were "street properties" rather than flats, which arguably helped to ghettoise the remaining council tenants on run-down inner city estates. In fact, in Crick's view, he deserves only limited credit; it had been a Conservative commitment since 1974, and much of the detailed work was done by his juniors Hugh Rossi (in opposition) and John Stanley (in government).
Sources: en.wikipedia.org
During the 1974 tours, he played through the quadraphonic vocal system of the Wall of Sound PA, with 9600 watts routed through more than two hundred speakers. The March 17, 1975 cancelled Grateful Dead studio session became a Seastones session with Crosby and included "Ned's Birthday Jam." Lagin and Lesh's 1974 interstitial performances are included in these live Grateful Dead albums:
== External links == Adrenomedullin at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Human ADM genome location and ADM gene details page in the UCSC Genome Browser. This article incorporates text from the United States National Library of Medicine, which is in the public domain.
=== Parkinson's disease === α-Synuclein is a protein that is associated with Parkinson's disease. In humans, this protein is encoded by the SNCA gene. α-Synuclein is involved in recycling synaptic vesicles that carry neurotransmitters and naturally occurs in an unfolded form. Elevated levels of α-Synuclein are found in patients with Parkinson's disease. There is a correlation between the concentration of unphosphorylated α-Synuclein present in the patient and the severity of Parkinson's disease. Specifically, phosphorylation of Ser129 in α-Synuclein has an impact on severity. Healthy patients have higher levels of unphosphorylated α-Synuclein than patients with Parkinson's disease. The measurement of change in the ratio of concentrations of phosphorylated α-Synuclein to unphosphorylated α-Synuclein within a patient could be a marker of the disease progression. Antibodies that target α-Synuclein at phosphorylated Ser129 are used to study the molecular aspects of synucleinopathies. Phosphorylation of Ser129 is associated with the aggregation of the protein and further damage to the nervous system. The aggregation of phosphorylated α-Synuclein can be enhanced if a presynaptic scaffold protein, Sept4, is present in insufficient quantities. Direct interaction of α-Synuclein with Sept4 inhibits the phosphorylation of Ser129. However, phosphorylation of Ser129 can be observed without synuclein aggregation in conditions of overexpression.
They were the first set of nonsense mutations to be discovered, isolated by Richard H. Epstein and Charles Steinberg and named after their friend and graduate Caltech student Harris Bernstein, whose last name means "amber" in German (cf. Bernstein). Viruses with amber mutations are characterized by their ability to infect only certain strains of bacteria, known as amber suppressors. These bacteria carry their own mutation that allows a recovery of function in the mutant viruses. For example, a mutation in the tRNA that recognizes the amber stop codon allows translation to "read through" the codon and produce a full-length protein, thereby recovering the normal form of the protein and "suppressing" the amber mutation. Thus, amber mutants are an entire class of virus mutants that can grow in bacteria that contain amber suppressor mutations. Similar suppressors are known for ochre and opal stop codons as well. tRNA molecules carrying unnatural aminoacids have been designed to recognize the amber stop codon in bacterial RNA. This technology allows for incorporation of orthogonal aminoacids (such as p-azidophenylalanine) at specific locations of the target protein.
In June 1884, British imperial interests were ignited in the discovery by Jan Gerrit Bantjes of what would prove to be the world's largest deposit of gold ore at an outcrop on a ridge 69 km (43 mi) south of the Boer capital at Pretoria. The ridge was known locally as the "Witwatersrand" (white water ridge, a watershed). A gold rush to the Transvaal brought thousands of British and other prospectors from around the globe and over the border from the Cape Colony, which had been under British control since 1806.
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.
Purity is normally stated as an area percentage from high-performance liquid chromatography, for example ninety-five or ninety-eight percent. That figure describes the proportion of ultraviolet-absorbing material eluting as the main peak. It says nothing about water content, counterions, residual solvents or mass fraction of the peptide itself.