Dynamics and orientation of transmembrane peptide from bacteriorhodopsin incorporated into lipid bilayer as revealed by solid state 31P and 13C NMR spectroscopy

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Abstract
13C and 31P NMR spectra of a transmembrane peptide, [1‐13C]Ala14‐labeled A(6–34), of bacteriorhodopsin incorporated into dimyristoylphosphatidylcholine (DMPC) bilayer were recorded to clarify its dynamics and orientation in the lipid bilayer. This peptide is shown to take an α‐helical form both in liquid crystalline and gel phases, as viewed from the conformation dependent 13C chemical shifts. In addition, this peptide undergoes rapid rigid‐body rotation about the helical axis at ambient temperature as viewed from the axially symmetric 13C chemical shift anisotropy, whereas this symmetric anisotropy is changed to an asymmetric pattern at temperatures below 10°C. We further incorporated the peptide into the spontaneously aligned DMPC bilayer to applied magnetic field, induced by dynorphin (dynorphin:DMPC =1:10), a heptadeca‐opioid peptide with very high affinity to opioid receptor, in order to gain insight into its orientation in the bilayer. This magnetically aligned system turned out to be persistent even at 0°C as viewed from 31P NMR spectra of the lipid bilayer, after this peptide was incorporated into this system [A(6–34): dynorphin: DMPC = 4:10:100]. It was found from the 13C NMR spectra of [1‐13C]Ala14 A(6–34) that the helical axis of A(6–34) is oriented parallel to the bilayer normal irrespective of the presence or absence of reorientation motion about the helical axis at a temperature above the lowered gel to liquid crystalline phase transition. © 2002 John Wiley & Sons, Inc. Biopolymers 63: 122–131, 2002
Funding Information
  • Ministry of Education, Science, Culture and Sports of Japan