Definition: One of the three major families of endogenous opioid peptides. The enkephalins are pentapeptides that are widespread in the central and peripheral nervous systems and in the adrenal medulla.
biphalin [ (Tyr-Ala-Gly-Phe-NH2)2,(tyrosyl-alanyl-glycyl-phenylalaninamide)dimer,D-ENK,D-ENK-O,DALA(2),bis(Tyr-Ala-Gly-PheNH2)hydrazide,bis(tyrosyl-alanyl-glycyl-phenylalaninamide)hydrazide ] enkephalin dimer; two fragments of Ala(2)-enkephalin are connected by a diamine bridge to form above cpd; structure given in first source