PT-141 Pen

PT-141 (Bremelanotide) is a synthetic peptide belonging to the class of melanocortin receptor ligands; chemically, it is a cyclic heptapeptide with an intramolecular lactam bridge. In scientific research, it is studied as a model compound for melanocortin receptor pharmacology and as a reference standard in analytical work. This compound is offered as a 3 ml pre-filled injection pen containing 10 mg, exclusively for laboratory and research purposes.

What is PT-141?

PT-141 is a cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, systematically designated as N-acetyl-L-norleucyl-L-α-aspartyl-L-histidyl-D-phenylalanyl-L-arginyl-L-tryptophyll-L-lysine-(2→7)-lactam. The ring is formed by the amide bond between the side chains of the aspartic acid and lysine, thereby fixing the molecule in a fixed spatial conformation; together with the D-configuration of the phenylalanine residue, this makes the peptide less susceptible to degradation by peptidases in vitro than a comparable linear motif. The compound is derived from the endogenous melanocortin peptide α-MSH and contains the conserved His-D-Phe-Arg-Trp core motif, described in the literature as the pharmacophore of this peptide family.

In research models, PT-141 is characterized as an agonist of the melanocortin receptors, a family of G-protein-coupled receptors referred to in the literature as MC1R through MC5R. In cell models expressing these subtypes, the measured response occurs via activation of adenylate cyclase and an increase in intracellular cAMP; this second-messenger response forms the basis for binding and activity determinations in vitro. Because the peptide does not target the subtypes equally, it serves as a comparison ligand in selectivity studies. Consequently, PT-141 is used as a model compound and reference substance within scientific research.

Research areas

In a laboratory context, PT-141 occurs in the following research areas, among others:

• Receptor research into G-protein-coupled melanocortin receptors (MC1R to MC5R) and the subtype selectivity of cyclic α-MSH analogues in vitro.
• Signal transduction study in which the cAMP response is monitored in cell lines expressing a melanocortin receptor.
• Structure-activity relationship study into the influence of the lactam bridge and D-phenylalanine substitution on receptor affinity.
• Biophysical modeling of conformation-restricted cyclic peptides and their enzymatic stability.
• Analytical method development and validation (HPLC, LC-MS) using PT-141 as the reference standard.
• Stability and solubility studies of freeze-dried peptides under controlled conditions.

Each of these applications involves controlled laboratory or preclinical model research.

PT-141 in our research range

This version belongs to the line of pre-filled injection pens: compounds contained in dissolved form in a sealed cartridge, so that a researcher does not need to go through their own dissolution step. The same compound is available elsewhere in the range as freeze-dried lyophilisate in a vial. Other compounds within the pen line act on a completely different biochemical system; the form indicates nothing about the substance class.

Specifications

Shape, handling and storage

The compound is dissolved in a sealed 3 ml glass cartridge in a pen with a click mechanism. A separate dissolution step is not required with this version; the cartridge remains closed until a needle is inserted. The label includes a table showing the relationship between click settings and dispensed volume, allowing sample collections to be reproducibly recorded in a protocol.

Store the pen refrigerated between 2 and 8 °C, protected from light and in the original packaging. Handle the pen in a clean working environment, use a new sterile needle for each draw to prevent cross-contamination, and wear standard personal protective equipment. Keep the material out of reach of unauthorized persons.

Composition and lab results

The raw material used has a controlled purity of ≥ 99% (HPLC). The pen contains PT-141 in a sterile aqueous base; the total amount of active substance per version is stated on the label.

Analysis certificates of the relevant parties are on our lab results page.

Frequently Asked Questions

To which chemical class does PT-141 belong?
PT-141 is a synthetic cyclic heptapeptide belonging to the group of melanocortin receptor ligands, derived from the endogenous peptide α-MSH. It is therefore not a small organic molecule, but a peptide with a defined amino acid sequence.

What role does the lactam bridge play in research?
The amide bond between the side chains of aspartic acid and lysine closes the molecule into a ring. This cyclization fixes the conformation and increases resistance to enzymatic degradation in vitro, making the compound a widely used model in structure-activity research.

In what form is the compound supplied?
As a pre-filled injection pen with a sealed 3 ml cartridge containing 10 mg. The box also contains ten sterile pen needles and alcohol wipes.

How do I store the pen?
Refrigerated between 2 and 8 °C, in a dark place and in the original packaging. Do not freeze.