Dermorphin

Dermorphin was isolated from the skin of Phyllomedusa tree frogs and has the sequence Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser. The D-alanine at position two is the structurally significant part: naturally occurring peptides are built almost exclusively from L-amino acids, and the discovery of a D-residue in a vertebrate peptide was itself a notable result.

That residue is also functional rather than incidental. It confers resistance to the peptidases that would otherwise degrade the chain rapidly, which is why the natural sequence is usable as a laboratory tool without modification.

Dermorphin is a high-affinity, highly selective agonist at the mu-opioid receptor. Selectivity is the entire point of its use: most opioid ligands act at more than one receptor subtype, so attributing an observed effect to a specific receptor is difficult. A selective agonist removes that ambiguity.

• Receptor binding and displacement assays, as a reference mu-selective ligand

• Separation of mu-mediated from kappa- and delta-mediated effects in animal behavioural work

• Antinociception research, where it is a standard comparator in analgesia models

• Peptidase-resistance studies, where the D-residue is the object of interest rather than the receptor

• Analytical and doping-control method development, where it is a known target analyte

Dermorphin is an opioid receptor agonist and is treated as a controlled substance in many jurisdictions. It is supplied here strictly as a laboratory reference material, and researchers are responsible for confirming the regulatory position that applies to them before ordering.

Within this catalogue the closest methodological neighbours are the other receptor-selective tool peptides — PT-141 at melanocortin receptors and Oxytocin at the oxytocin receptor — rather than anything sharing its target.