MT2

Description

Compound Specifications

Common name	MT2 (Melanotan II)
Compound class	Cyclic melanocortin peptide
Structure	Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-NH₂
Amino acid count	7
Cyclization	Lactam bridge, Asp–Lys side chains
C-terminus	Amidated
Non-standard residues	Nle (norleucine), D-Phe
Molecular weight	1024.2 g/mol
CAS number	121062-08-6
Form	Lyophilized powder
Quantity	10mg per vial
Purity	≥99% (HPLC verified)
Storage (lyophilized)	2–8°C, protected from light
Storage (reconstituted)	2–8°C, 30 days
Third-party testing	Freedom Diagnostics

Verify structure, molecular weight and CAS number against batch COA prior to publication.

The Structural Relationship to PT-141

MT2 and PT-141 are among the most frequently confused compounds in this market, and the reason is that they are nearly the same molecule.

Both are cyclic heptapeptides with the same ring composition, the same lactam bridge between aspartate and lysine side chains, the same acetylated norleucine, the same norleucine and D-phenylalanine substitutions. Their molecular weights differ by approximately one unit.

The difference is at the C-terminus. MT2 is amidated; PT-141 terminates in a free carboxylic acid. In structural terms this is the smallest possible distinction between two peptides — a single functional group at one end.

Its consequences are not proportionally small. An amide carries no charge; a free carboxylic acid is deprotonated and negatively charged at neutral pH. That charge difference at a terminus adjacent to the binding region alters receptor selectivity across the melanocortin receptor subtypes, which is why the two compounds are characterized differently in the literature despite their structural near-identity.

The practical implication for anyone sourcing either compound is that they cannot be distinguished by appearance, and a supplier’s label is not verification. A Certificate of Analysis reporting molecular weight is the only reliable way to establish which compound is in a given vial. This is a case where the difference between what was ordered and what was received is a single functional group and roughly one mass unit.

All statements above describe molecular characteristics. Noxa Labs makes no claim regarding safety, efficacy, or outcomes of any kind, in humans or animals.

Handling & Storage

Lyophilized MT2 is stable at 2–8°C when sealed and shielded from light. For storage beyond several months, -20°C is preferred.

Light protection required. The sequence contains tryptophan, the most photosensitive of the standard amino acids. Use amber vials or wrap in foil, and minimize bench time.

Introduce bacteriostatic water slowly down the inner wall of the vial. Swirl gently until fully dissolved; do not shake or vortex. Cyclic peptides are conformationally rigid and dissolve without difficulty. The solution should be clear and particulate-free.

Once in solution, store at 2–8°C, protected from light, and use within 30 days. A 10mg vial reconstituted with 2mL of bacteriostatic water yields a 5mg/mL concentration.

Concentration and volume calculator →

Purity & Testing

Every batch is synthesized at our GMP-compliant Arizona facility and independently analyzed by Freedom Diagnostics before release. Given the mass proximity of this compound to PT-141, we regard mass verification on this product as particularly consequential. Certificates of Analysis are available for any lot; contact us with your order number.

View all Certificates of Analysis →

Frequently Asked Questions

How does MT2 differ from PT-141?
The C-terminus. MT2 is amidated; PT-141 is a free acid. The structures are otherwise identical and the molecular weights differ by roughly one unit.

Can the two be told apart without testing?
No. They are visually indistinguishable. A Certificate of Analysis reporting molecular weight is the only reliable means of identification.

What does cyclization do?
A lactam bridge between the aspartate and lysine side chains closes the sequence into a ring, restricting conformation and blocking exopeptidase access.

Why does this compound need light protection?
It contains tryptophan, which is highly photosensitive.

Related Research Compounds

• PT-141 10mg — structurally near-identical, free acid C-terminus
• Certificates of Analysis — batch testing data

Research Use Only

For Research Use Only. This product is intended solely for laboratory research purposes. It is not a drug, food, or cosmetic and may not be misbranded, misused, or mislabeled as such. This compound has not been approved by any regulatory authority for any use, and published literature has raised safety concerns regarding its administration to humans. Not for human or veterinary use. Not for diagnostic or therapeutic use. Not for resale without authorization.