the former group includes leu5-enkephalin , met5-enkephalin , met5-enkephalin-arg6-phe7 , beta-lipotropin , and gamma-endorphin , while the nonreactive opioid peptides include alpha-neo-endorphin , beta-neo-endorphin , dynorphin , and beta-endorphin .
C0014298
enkephalin
C0205753
opioid peptides