Beta-neoendorphin

Where it comes from

Made in

Made from alpha-neoendorphin by a carboxypeptidase

Sent out by

With the dynorphins

Acts on

• Kappa receptors

What it does

• Acts like alpha-neoendorphin, a little less potently in bioassay ³
• Shows how a single cut tunes an opioid: taking off one lysine changes the potency and not the receptor ¹
• Found in the same granules as alpha-neoendorphin, in a ratio set by how far the carboxypeptidase has gone ²

In medicine

• No medicine copies it, and it is not measured outside research laboratories
• The kappa medicines nalfurafine and difelikefalin act at its receptor; nothing acts on the peptide itself

Beyond the body’s own use

• Nothing containing it is in trials, and no analogue of it has been given to a person
• Its value is as evidence that prodynorphin processing is graded rather than all or nothing: one granule holds a ten-residue and a nine-residue peptide that differ only in strength ¹²
• What is unknown is whether the difference matters in the body. No tissue is known to hold one without the other and no experiment has separated their effects, so the shorter peptide is treated as a slightly weaker version of the longer ³