title: Switched-angle spinning applied to bicelles containing phospholipid-associated peptides.
abstract: In a model study, the proton NMR spectrum of the opioid pentapeptide leucine-enkephalin associated with bicelles is investigated. The spectral resolution for a static sample is limited due to the large number of anisotropic interactions, in particular strong proton-proton couplings, but resolution is greatly improved by magic-angle sample spinning. Here we present two-dimensional switched-angle spinning NMR experiments, which correlate the high-resolution spectrum of the membrane-bound peptide under magic-angle spinning with its anisotropic spectrum, leading to well-resolved spectra. The two-dimensional spectrum allows the exploitation of the high resolution of the isotropic spectrum, while retaining the structural information imparted by the anisotropic interactions in the static spectrum. Furthermore, switched-angle spinning techniques are demonstrated that allow one to record the proton spectrum of ordered bicellar phases as a function of the angle between the rotor axis and the magnetic field direction, thereby scaling the dipolar interactions by a predefined factor.
authors.affiliation: Physical Chemistry, ETH Zurich, ETH-Hönggerberg, CH-8093 Zurich, Switzerland.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Zandomeneghi
authors.forename: Philip T F
authors.initials: PT
authors.lastname: Williamson
authors.forename: Andreas
authors.initials: A
authors.lastname: Hunkeler
authors.forename: Beat H
authors.initials: BH
authors.lastname: Meier
mesh_terms: D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D004743:Enkephalin, Leucine / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008962:Models, Theoretical; D008968:Molecular Conformation; D009842:Oligopeptides / Q000737:chemistry*; D010742:Phospholipid Ethers / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*
chemical_list: C052298:1,2-dihexadecyl-sn-glycero-3-phosphocholine; D008081:Liposomes; D009842:Oligopeptides; D010742:Phospholipid Ethers; D010743:Phospholipids; D004743:Enkephalin, Leucine; D004134:Dimyristoylphosphatidylcholine