title: Detection of peptide-phospholipid interaction sites in bilayer membranes by 13C NMR spectroscopy: observation of 2H/31P-selective 1H-depolarization under magic-angle spinning.
abstract: We have developed a solid-state NMR method for observing the signals due to 13C spins of a peptide in the close vicinity of 31P and 2H spins in deuterated phospholipid bilayers. The signal intensities in 13C high-resolution NMR spectra directly indicate the depolarization of 1H by 1H-31P and 1H-2H dipolar couplings under multiple-contact cross-polarization. This method was applied to a fully 13C-, 15N-labeled 14-residue peptide, mastoparan-X (MP-X), bound to phospholipid bilayers whose fatty acyl chains are deuterated. The 13C NMR spectra for the depolarization were simulated from the chemical shifts and structure of membrane-bound MP-X previously determined and the distribution of 2H and 31P spins in lipid bilayers. The minimization of RMSD between the simulated and the experimental spectra showed that the amphiphilic alpha-helix of MP-X was located in the interface between the water layer and the hydrophobic domain of the bilayer, with nonpolar residues facing the phosphorus atoms and alkyl chains of the lipids.
authors.affiliation: Institute for Protein Research, Osaka University, Suita, 565-0871, Japan, and Japan Biological Informatics Consortium, Chuo-ku, Tokyo 104-0032, Japan.
authors.forename: Erisa
authors.initials: E
authors.lastname: Harada
authors.forename: Yasuto
authors.initials: Y
authors.lastname: Todokoro
authors.forename: Hideo
authors.initials: H
authors.lastname: Akutsu
authors.forename: Toshimichi
authors.initials: T
authors.lastname: Fujiwara
mesh_terms: D002247:Carbon Isotopes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008567:Membranes, Artificial; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D002247:Carbon Isotopes; D008567:Membranes, Artificial; D010455:Peptides; D010743:Phospholipids