On the Combined Analysis of H-2 and N-15/H-1 Solid-State NMR Data for Determination of Transmembrane Peptide Orientation and Dynamics
by Vostrikov, V. V.; Grant, C. V.; Opella, S. J.; Koeppe, R. E.
The dynamics of membrane-spanning peptides have a strong affect on the solid-state NMR observables. We present a combined analysis of H-2-alanine quadrupolar splittings together with N-15/H-1 dipolar couplings and N-15 chemical shifts, using two models to treat the dynamics, for the systematic evaluation of transmembrane peptides based on the GWALP23 sequence (acetyl-GGALW(LA)(6)LWLAGA-amide). The results indicate that derivatives of GWALP23 incorporating diverse guest residues adopt a range of apparent tilt angles that span 5 degrees-35 degrees in lipid bilayer membranes. By comparing individual and combined analyses of specifically H-2- or N-15-labeled peptides incorporated in magnetically or mechanically aligned lipid bilayers, we examine the influence of data-set size/identity, and of explicitly modeled dynamics, on the deduced average orientations of the peptides. We conclude that peptides with small apparent tilt values (