'Beta' Methylation of the Phe7 and Trp9 melanotropin side chain pharmacophores affects ligand-receptor interactions and prolonged biological activity - Haskell-Luevano, Carrie; Toth, Kate; Boteju, Lakmal; Job, Constatin; Castrucci, Ana Maria de Lauro; Hadley, Mac E; Hruby, V J (Jornal of Medicinal Chemistry, 1997)