What is PT-141?
PT-141 is a synthetic cyclic heptapeptide belonging to the class of melanocortin-family peptide analogs studied in receptor-signaling research. It is cataloged under CAS number 189691-06-3, with a molecular formula of C50H68N14O10 and a molecular weight of 1025.16. The compound is composed of seven amino acid residues arranged in a constrained macrocyclic architecture rather than a linear chain.
Structurally, PT-141 is defined by the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, in which a side-chain lactam bridge is formed between the aspartic acid (Asp) and lysine (Lys) residues. This intramolecular bridge cyclizes the core hexapeptide segment, imposing conformational rigidity on the molecule. The N-terminus is acetylated, and the incorporation of norleucine (Nle) and a D-configured phenylalanine (D-Phe) contribute to the peptide's resistance to proteolytic degradation. Together, these modifications distinguish PT-141 from unmodified linear peptides and define its identity as a well-characterized reference analyte (full sequence per COA).
Within the scientific literature, PT-141 is associated with melanocortin receptor research and related in-vitro and preclinical investigational models. In the research-chemical context it functions strictly as a laboratory reference material and biochemical tool for structure-activity, receptor-binding, and analytical method development studies. It is intended solely for research use and is not a drug, dietary supplement, cosmetic, or article intended for human or veterinary use.
Reconstitution & handling
As a lyophilized peptide, PT-141 is typically reconstituted in the laboratory by introducing a compatible aqueous solvent directly against the interior wall of the vial and allowing the powder to dissolve without vigorous agitation. Bacteriostatic water or sterile water is the most common vehicle for this peptide class; the presence of a strongly basic arginine residue, together with a histidine residue and the free C-terminal carboxyl group, generally supports good aqueous solubility, and a small proportion of dilute acetic acid can assist dissolution of peptides that are slow to enter solution. Swirling gently or letting the sealed vial stand undisturbed is preferred over shaking, which can introduce shear stress and foaming that may compromise the integrity of the constrained macrocyclic structure.
Reconstitution should be performed under clean technique, and the resulting solution is generally clear and colorless when the material has fully dissolved. Because peptides in solution are less stable than the dry solid, only the volume of solvent needed for immediate research work is typically prepared, and solutions are handled cold and protected from prolonged light exposure. This handling guidance is chemical in nature and does not constitute administration or dosing instruction.
Storage & stability
In its lyophilized form, PT-141 is best stored sealed and protected from light, moisture, and heat; short-term storage is commonly at refrigerated temperatures (2–8 °C), while extended storage of the dry powder is typically at −20 °C or colder, where the material remains stable over long periods. Once reconstituted, the peptide is markedly less stable and should be kept refrigerated and used within a limited window, with aliquoting and freezing employed to minimize repeated freeze-thaw cycles that can degrade peptide integrity. Allowing sealed vials to equilibrate to room temperature before opening helps limit condensation and moisture uptake into the hygroscopic solid.
How it's tested
The identity and purity of PT-141 are verified analytically prior to release. Reversed-phase high-performance liquid chromatography (HPLC) is used to quantify chromatographic purity, which is confirmed at ≥99% for this material, resolving the target peptide from process-related impurities and any residual synthesis byproducts. Mass spectrometry (MS) provides orthogonal confirmation of identity by matching the observed mass to the expected molecular weight of 1025.16 for the C50H68N14O10 composition, and can confirm correct formation of the lactam-bridged cyclic species. A Certificate of Analysis (COA) accompanies the material and documents these results along with the confirmed sequence, so that researchers can independently verify lot-specific identity, purity, and molecular characterization.