Nuclear magnetic resonance characterization of the myristoylated, N-terminal fragment of ADP-ribosylation factor 1 in a magnetically oriented membrane array.

The behavior of the N-terminal fragment of human ADP-ribosylation factor 1 (ARF1) in a membranelike environment is described. This is accomplished using heteronuclear liquid crystal NMR techniques in a magnetically oriented membrane array on a selectively 13C- and 15N-labeled peptide. After full assignment of the labeled sites, residual dipolar couplings (13C-13C, 15N-1H and, 13C-15N) and chemical shift anisotropy effects (amide 13C and 15N) were measured. The experimental data were interpreted using order matrix calculations to yield orientational and dynamic information for four separate, rigid amide planes. The experimental data obtained proves that the amphipathic peptide interacts with the bilayer in a mode that is consistent with an alpha-helix having its axis parallel to the membrane surface. Possibilities of extending the employed techniques to larger and uniformly labeled systems are discussed.