Melanotan II (MT2) 10 mg

What is MT2?

MT2 is the catalogue name for Melanotan II, also listed in the literature as MT-II or Melanotan-II. It is a fully synthetic, cyclic peptide from the melanocortin family. Its scaffold is derived from the core segment 4–10 of α-melanocyte-stimulating hormone (α-MSH), whose natural sequence comprises 13 amino acids. Pharmacologically, Melanotan II is classed as a non-selective agonist at melanocortin receptors: it addresses several subtypes of this receptor family rather than targeting a single one.

Structure and key data

MT2 is derived from this α-MSH core segment by four substitutions: norleucine at position 4, aspartic acid at position 5, D-phenylalanine at position 7 and lysine at position 10. The side chains of aspartic acid and lysine are joined to each other by an amide bond, known as a lactam bridge. This creates a ring of six amino acids, preceded by the acetylated norleucine; the C-terminus is present as an amide.

• Sequence: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2
• One-letter code of the core: XDHfRWK (X = norleucine, f = D-phenylalanine)
• Molecular formula: C50H69N15O9
• Molar mass: 1024.2 g/mol (free form, without counter-ions)
• CAS number: 121062-08-6
• PubChem CID: 92432

Classification: MT2 and related peptides

The same section of the catalogue lists MT1 (Melanotan I). Both are derived from α-MSH but differ fundamentally in structure: MT1 is a linear chain of 13 amino acids with only two substitutions compared with the natural sequence, whereas MT2 is shortened to seven residues and fixed in a ring by the lactam bridge. The literature assigns MT1 to the MC1 receptor, while MT2 is described as a non-selective agonist across several subtypes. KPV, the C-terminal tripeptide lysine-proline-valine, is also derived from the α-MSH sequence; this is precisely the section that MT2 lacks. An overview of all molecules in this group is given in the Melanocortins & Copper Peptides category.

Research context

In in-vitro and preclinical work, Melanotan II serves as a tool compound for studying the melanocortin system. At the cellular level this concerns, for example, signalling via the MC1 receptor in melanocyte cultures; in rodent models, central signalling pathways via the MC4 and MC3 receptors. Because the substance addresses several subtypes, it is used as a non-selective reference agonist in studies with knockout lines for individual receptors (such as MC3R or MC4R). The comparison between wild type and knockout then shows what proportion of a signal depends on a particular receptor.

Analytics at GPeptides

MT2 is listed as a 10 mg vial with a purity of ≥ 98 % (HPLC). Ideally, a single main peak dominates the chromatogram; secondary peaks can point, for instance, to truncated sequences or to ring precursors that have not been closed. Mass spectrometry checks identity against the molecular formula C50H69N15O9: the expected monoisotopic mass is around 1023.54 Da, the average mass around 1024.2 Da. Since the lactam bridge forms with the loss of water, an open, linear precursor lies about 18 Da higher – a difference that MS detects unambiguously. MT2 is regularly tested externally by HPLC and mass spectrometry; the measurements are carried out by an independent external laboratory. Available certificates of analysis (COA) can be found in the lab area; where no certificate has been filed, testing is considered pending. How to read the chromatogram and mass spectrum is explained in the guide HPLC and mass spectrometry.