4-(Hydroxyphenyl)azo-leucine enkephalin 76995-91-0 Enkephalin-leu, 4-(hydroxyphenyl)azo- L-Leucine, N-(4-((hydroxyphenyl)azo)-N-(N-(N-L-tyrosylglycyl)glycyl)-L-phenylalanyl)- Leu-enkephalin-4-(hydroxyphenyl)azo TGGAP