What is PT-141?
PT-141 appears in our molecular records under CAS 189691-06-3 with the formula C50H68N14O10, an average molecular weight of 1025.16 and the synonym bremelanotide. No residue-by-residue sequence is carried for the entry, so none is reproduced here.
Set beside the Melanotan-2 record in the same dataset, the relationship is visible in the formulas alone. Both carry fifty carbon atoms, and the pair differs by one nitrogen exchanged for one oxygen with a hydrogen lost, the signature of a C-terminal carboxamide replaced by a free carboxylic acid. That change at the tail of an otherwise shared scaffold underlies the different receptor preference the two show in binding studies.
In the literature the compound behaves as a melanocortin agonist with a preference for MC4R and MC1R over the other subtypes. Cell assays use it as an MC4R reference agonist, and rodent studies have probed central melanocortin control of sexual behaviour, feeding and blood pressure. Selectivity against MC3R varies between reports, the downstream central circuitry is only partly mapped, and the contribution of peripheral receptors to animal readouts is disputed.
Reconstitution & handling
Bacteriostatic water suits a vial drawn from more than once, sterile water a single preparation. Add the diluent against the inside wall, let it wet the cake, then swirl until clear rather than shaking. Working concentration is the labelled peptide mass divided by the diluent volume, with net peptide content applied when a molar figure is required.
Storage & stability
The dry cake keeps best sealed at -20 °C with desiccant and no light. After reconstitution, refrigerate at 2 to 8 °C, aliquot into single-use volumes and avoid repeat freezing, since melanocortin analogues in dilute solution tolerate cold standing better than thermal cycling. Amber or foil-wrapped containers are standard for this class, and a cold vial should reach room temperature before opening so condensation does not reach the powder.
How it's tested
Each lot is released on reversed-phase HPLC purity at 214 and 220 nm against a 99 percent or better main-peak threshold, with identity checked by mass spectrometry against the theoretical average mass of 1025.16. Net peptide content is reported separately because the material is supplied as a salt. Water content is measured on the cake, and a lot-matched certificate of analysis is available on request.