The micelle-associated 3D structures of Boc-Y(SO₃)-Nle-G-W-Nle- D-2-phenylethylester (JMV-180) and CCK-8(s) share conformational elements of a calculated CCK₁ receptor-bound model

JMV-180 (1) and CCK-8(s) are high affinity ligands at the CCK₁ receptor that have similar and different actions via this receptor. Here we calculate the tertiary structure of 1 or CCK-8(s) in the presence of dodecylphosphocholine micelles at pH 5.0 and 35°C from 2D ¹H NMR data recorded at 600 MHz. The NMR derived 3D structures of 1 and CCK-8(s) share a common type I β-turn around residues Nle3/M3 and G4 and diverge from each other structurally at the N- and C-termini. The fluorescence and circular dichroism spectral properties of these peptides are consistent with their NMR derived structures. The structures determined in the presence of DPC micelles are compared to available models of 1 or CCK-8(s) bound to the CCK₁ receptor. For CCK and 1, these comparisons show that DPC micelle associated structures duplicate some important aspects of the models calculated from cross-linking derived constraints at the CCK₁ receptor.