PT-141, also known as bremelanotide, is a synthetic peptide with the following structure:
Ac-Nle-cyclo(-Asp-His-D-Phe-Arg-Trp-Lys)-OH
This means that PT-141 is a chain of seven amino acids, starting with the N-acetyl group and ending with the hydroxyl group. The amino acids in the sequence are:
- Nle: Norleucine
- Asp: Aspartic acid
- His: Histidine
- D-Phe: D-Phenylalanine
- Arg: Arginine
- Trp: Tryptophan
- Lys: Lysine
The cyclo() portion of the structure indicates that the peptide is cyclized, meaning that the N-terminal and C-terminal ends of the peptide chain are linked together. This cyclization makes PT-141 more stable and resistant to proteolytic degradation.
The structure of PT-141 is similar to the structure of alpha-melanocyte stimulating hormone (α-MSH), a naturally occurring peptide hormone that binds to and activates melanocortin receptors. Melanocortin receptors are involved in a variety of physiological functions, including appetite, energy metabolism, and sexual behavior.
PT-141 is a more potent and selective agonist of melanocortin receptors than α-MSH. This means that PT-141 binds to melanocortin receptors with greater affinity and produces more pronounced effects.
The structure of PT-141 is also important for its ability to penetrate the blood-brain barrier and act in the central nervous system. The blood-brain barrier is a protective barrier that separates the bloodstream from the brain. Many drugs cannot cross the blood-brain barrier, which limits their ability to act in the brain.
However, PT-141 is able to cross the blood-brain barrier and bind to melanocortin receptors in the brain. This allows PT-141 to produce its effects on sexual desire, arousal, and function.
The structure of PT-141 is still under investigation, but scientists are learning more about how it works and how it can be used to treat sexual dysfunction.
