PT-141, or Bremelanotide, is a research peptide that’s currently being tested for its affects on sexual dysfunction. PT 141 is a metabolite of Melanotan 2, or MT-2 (the tanning peptide), that’s missing the C Terminal amide group. PT 141 is a peptide which is a chain of 2 or more amino acids linked by amide bonds. Amide bonds are also called peptide bonds. The Bremelanotide peptide is a chain of amino acids in the following sequence: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH. Molecular Formula: C50H68N14O10 PT-141 Structural Names: cyclo-[Nle4, Asp5, D-Phe7, Lys10]alpha-MSH-(4-10) Sequence: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH CAS number: 189691-06-3 Molar Mass: 1025.2 g/mol PubChem: CID 9941379