Effects of Membrane Peptide Dynamics on High-Resolution Magic-Angle Spinning NMR Effets de la dynamique d’un peptide membranaire sur un spectre RMN haute résolution en rotation a l’angle magique

In the past fifteen years, interference between molecular dynamics and coherent manipulation of nuclear magnetization in nuclear magnetic resonance (NMR) experiments such as spin decoupling, cross-polarization or magic-angle spinning (MAS) have been identified and studied carefully. Recent experiments performed in our laboratory on model compounds have provided insight into the nature of a perturbation responsible for the broadening of 13C and 15N signals, namely the interference of some molecular motion with 1H-decoupling. The same effect is demonstrated here for the first time in the case of a membrane peptide, gramicidin A (gA), in an hydrated lipid bilayer. The present experiment provides the first successful attempt to observe high-resolution solid-state 13C NMR spectra of a Cα moiety in membrane peptide contained in a lipid bilayer. Furthermore, the development of strategies to circumvent the broadening effect allows the extraction of relevant data concerning the dynamics of gA under physiological conditions. key words : Gramicidin, membrane, dynamics, 1H-decoupling