76995-89-6 Azo-enkephalin Azoenkephalin Enkephalin-leu, 4-(5-(2-amino-2-carboxyethyl)-2-hydroxyphenyl)azo- L-Leucine, glycylglycyl-4-((5-(2-amino-2-carboxyethyl)-2-hydroxyphenyl)azo)-L-phenylalanyl-, cyclic (3-1)-peptide