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Preproenkephalin A.
Preproenkephalin A.
Calotte model of Met-Enkephalin according to PDB  1PLW
Properties of human protein
Mass / length primary structure 267 aa; 30.8 kDa
Gene name PENK
External IDs
Parent taxon Jaws
human mouse
Entrez 5179 18619
Ensemble ENSG00000181195 ENSMUSG00000045573
UniProt P01210 Q68G73
Refseq (mRNA) NM_006211 NM_001002927
Refseq (protein) NP_006202 NP_001002927
Gene locus Chr 8: 57.52 - 57.52 Mb Chr 4: 4.06 - 4.07 Mb
PubMed search 5179 18619

The enkephalins ( ancient Greek ἐγκέφαλος enképhalos " brain ") are endogenous pentapeptides from the class of opioid peptides . These are opioids produced by the body itself . This family consists of two connections that play an important role in the perception of pain . The other two families of opioid peptides are the endorphins and the dynorphins .

Discovery and Structure


The two neuropeptides were discovered in 1975. In the peptide sequence they differ in the fifth amino acid . Met-Enkephalin has the sequence Tyr - Gly - Gly - Phe - Met and Leu-Enkephalin has the sequence Tyr-Gly-Gly-Phe- Leu .


See main article Opioid Receptor

The receptor for the two enkephalins are the opioid receptors , which belong to the group of G-protein-coupled receptors . There the two enkephalins act as the body's own pain relievers.


The gene coding for the two neuropeptides is called proenkephalin (PENK). In humans, it is on chromosome 8 , gene locus q23-q24. The Met-enkephalin sequence is encoded by both the enkephalin gene and the endorphin gene (POMC gene), while the sequence of the Leu-enkephalin is encoded by both the enkephalin gene and the dynorphin gene.


Web links

Individual evidence

  1. External identifiers of or database links for Met-Enkephalin : CAS number: 58569-55-4, EC number: 261-335-8, ECHA InfoCard: 100.055.741 , PubChem : 6427062 , ChemSpider : 391597 , Wikidata : Q1960495 .
  2. External identifiers or database links for Leu-Enkephalin : CAS number: 58822-25-6, EC number: 261-457-1, ECHA InfoCard: 100.055.852 , PubChem : 461776 , ChemSpider : 406229 , Wikidata : Q6533903 .
  3. RS Rapaka, RL Hawks: Opioid peptides: Molecular pharmacology, biosynthesis and analysis In: National Institute on Drug Abuse , Research Monograph # 70, 1986.