Structural and analytical reference
Compare Melanotan-1 and Melanotan-2 by backbone size, cyclization, nonstandard residues and exact analytical identity. Research reference only.
Melanotan-1 is associated with the 13-residue NDP-alpha-MSH/afamelanotide identity. Melanotan-2 is a distinct cyclic seven-residue analogue. The main structural distinction is the complete architecture, not simply the shared melanotan name.
Structure at a glance
| Attribute | Melanotan-1 | Melanotan-2 |
|---|---|---|
| Reference identity | NDP-alpha-MSH; afamelanotide | Melanotan-II cyclic analogue |
| Backbone size | 13 residues | 7 residues |
| Architecture | Linear peptide | Side-chain lactam-cyclized peptide |
| Key substitutions/context | Norleucine and D-phenylalanine in an alpha-MSH analogue | Shorter analogue with a defined lactam bridge |
| Identity check | Complete chain, modifications and salt declaration | Sequence, ring closure, modifications and salt declaration |
The afamelanotide label is a reference for that specified regulated formulation. Its existence does not make a research vial labeled MT-1 equivalent to the labeled product.
What cyclic means here
Cyclization refers to a covalent connection within the declared structure. In the Melanotan-II design, the lactam bridge connects side-chain groups. It should not be inferred from a sequence written only as a linear string of residues.
A structural drawing or explicit cyclization annotation helps define the intended molecule. An expected molecular profile should include that ring closure and the terminal groups. The method used to support identity must be interpreted against this complete specification.
Names, derivatives and mass assignments
MT-1, MT-2, melanotan-I and melanotan-II are useful search aliases, but a purchase or analytical record needs more than an alias. Confirm sequence, stereochemistry, cyclization, acetylation, terminal amide and the supplied chemical form.
An acetate salt is not the same thing as an N-terminal acetyl group. Both terms can appear in peptide descriptions and refer to different chemistry. When comparing mass values, also distinguish average molecular mass from a monoisotopic value or an ion’s mass-to-charge ratio.
Read the actual batch record
Review the available SRL MT-1 sample record and SRL MT-2 sample record as separate documents. Sample identity, reported method and lot designation should remain attached to each record.
- Verify the declared molecule before comparing the percentages.
- Ask what structural evidence supports the cyclic identity.
- Keep purity, content and microbiological testing as separate attributes.
- Confirm the current fulfillment lot rather than inferring it from an archived sample.
Frequently asked questions
Is Melanotan-2 simply a smaller amount of Melanotan-1?
No. It is a different molecular structure, with a shorter backbone and cyclization.
Does a matching purity percentage mean the molecules are equivalent?
No. A percentage does not erase sequence or architectural differences.
Does this guide provide tanning or administration advice?
No. It addresses chemical identity and analytical documentation for research review.
Continue learning
Sources and scope
- DailyMed, Scenesse description. Official afamelanotide structural reference; regulated formulation details are not transferred to SRL materials.
- Al-Obeidi et al. (1989), cyclic lactam alpha-melanotropin analogues. Primary cyclic-design reference.
- Dorr et al. (1996), Melanotan-II study. Identifies the cyclic heptapeptide; clinical outcomes and administration are outside this reference.
This original SRL reference uses the linked scientific and labeling records for molecular or analytical context. It does not reproduce an experimental protocol or certify a supplier batch. Prepared October 2, 2026.
