An enkephalin is one of the first endorphins that were discovered in the brain. They are found in many parts of the brain, specially in the basal ganglia. They act as "natural pain killers".
Enkephalins are small proteins. They consist of five amino acids in each of their molecules. The last amino acid is either leucine (leu) or methionine (met).
Enkephalin is a brain neurotransmitter that is formed when tyrocine, glycine, glycine, phenylalanine, and methionine through a condensation reaction or dehydration synthesis.