most interestingly , synthesis of ac- [ nle4 , xxx5 , yyy7 , zzz10 ] alpha-msh4-10-nh2 analogues where xxx = asp or glu , yyy = phe or d-phe , and zzz = basic amino acids ( lys , orn , alpha , gamma-diaminobutyric acid ( dab ) , and alpha , beta-diaminopropionic acid ( dpr ] provided melanotropins with potencies up to 10 times that of the native hormone in stimulating frog ( rana pipiens ) skin darkening and 8-50 times more potent than alpha-msh in stimulating lizard ( anolis carolinensis ) skin melanophores in vitro .
C0301714
basic amino
C0024337
lys