the mu-agonists , [ d-ala2 , mephe4 , gly-ol5 ] enkephalin and morphine , displaced a small portion of the binding of [ 3h ] - [ d-pen2 , d-pen5 ] enkephalin with high affinities .
C0014298
enkephalin
C0525856
d-pen2 , d-pen5 ] enkephalin