Leu-Enkephalin

Leu-enkephalin is a pentapeptide comprising L-tyrosine, glycine, glycine, L-phenylalanine and L-leucine residues joined in sequence by peptide linkages. It is an endogenous opioid peptide produced in vertebrate species, including rodents, primates and humans that results from decomposition of proenkephalin or dynorphin and exhibits antinociceptive properties. It has a role as a neurotransmitter, an analgesic, a mu-opioid receptor agonist, a delta-opioid receptor agonist, a human metabolite and a rat metabolite. It is functionally related to a glycine, a L-leucine, a L-phenylalanine and a L-tyrosine. It is a tautomer of a Leu-enkephalin zwitterion.