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Chemical structure of kyotorphin
Systematic name L-Arginine, L-tyrosyl-
Other names kiotorphin
Chemical formula C15H23N5O4
Molecular mass 337.374 g/mol
Density g/cm3
Melting point xx.x °C
Boiling point xx.x °C
CAS number 70904-56-2
Disclaimer and references

Kyotorphin (L-tyrosyl-L-arginine) is a neuroactive dipeptide which plays a role in pain regulation in the brain. It was first isolated from bovine brain by Japanese scientists in 1979[1]. Kyotorphin was named for the site of its discovery, Kyoto, Japan and because of its morphine- (or endorphin-) like analgesic activity. Kyotorphin has an analgesic effect, but it does not interact with the opioid receptors. Instead, it acts by releasing an Met-enkephalin and stabilizing it from degradation. It may also possess properties of neuromediator/neuromodulator. It has been shown that kyotorphin is present in the human cerebrospinal fluid and that it is lower in patients with persistent pain[2].


  1. Takagi H, Shiomi H, Ueda and Amano H (1979) A novel analgesic dipeptide from bovine brain is a possible met-enkephalin releaser. Nature (Lond) 282: 410-412.
  2. K, Kaya K, Hazato T, Ueda H, Satoh M, Takagi H. (1991) Kyotorphin like substance in human cerebrospinal fluid of patients with persistent pain Masui. Nov;40(11):1686-90.