The chemical Met-Enkephalin-Arg-Phe has a known molecular formula of C42-H56-N10-O9-S. Synonyms may include: Enkephalin-met, arg(6)-phe(7)-, 6-Arg-7-phe-met-enkephalin, Enkephalin met, heptapeptide, Enkephalin-met, arginyl(6)-phenylalanine(7)-, Met-enk-AP, Met-enkephalin, arg(6)-phe(7)-, Methionine-enkephalin, arg(6)-phe(7)-, Tyr-gly-gly-phe-met-arg-phe, Tyrosyl-glycyl-glycyl-phenylalanyl-methionyl-arginyl-phenylalanine (ChemID).