title: Secondary structure and location of a magainin analogue in synthetic phospholipid bilayers.
abstract: Magainins are cationic, membrane-active peptides which show broad-spectrum antimicrobial activity. We have investigated the secondary structure and location of an analogue of magainin 2 in synthetic phospholipid bilayers using a combination of Fourier transform infrared (FTIR) spectroscopy and solid-state nuclear magnetic resonance (NMR) spectroscopy. Ala19-magainin 2 amide exhibits both alpha-helix and beta-sheet secondary structures in lipid bilayers containing either dipalmitoylphosphatidylglycerol (DPPG) or a 1:1 molar mixture of DPPG and dipalmitoylphosphatidylcholine (DPPC). The combination of FTIR and solid-state NMR results suggests that there are two populations of peptide. The secondary structure of one population is alpha-helix while that of the other population is beta-sheet. We demonstrate that the solid-state NMR technique, rotational-echo double resonance (REDOR), can be used to measure both intra- and intermolecular dipole-dipole interactions in membrane-bound peptides. Our REDOR experiments indicate that alpha-helical Ala19-magainin 2 amide is bound near the phospholipid head groups.
authors.affiliation: Department of Chemistry, Washington University, St. Louis, Missouri 63130, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Hirsh
authors.forename: J
authors.initials: J
authors.lastname: Hammer
authors.forename: W L
authors.initials: WL
authors.lastname: Maloy
authors.forename: J
authors.initials: J
authors.lastname: Blazyk
authors.forename: J
authors.initials: J
authors.lastname: Schaefer
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D023181:Antimicrobial Cationic Peptides; D004926:Escherichia coli / Q000187:drug effects; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D054806:Magainins; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D010743:Phospholipids / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D017550:Spectroscopy, Fourier Transform Infrared; D013211:Staphylococcus aureus / Q000187:drug effects; D013696:Temperature; D029867:Xenopus Proteins
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D008051:Lipid Bilayers; D054806:Magainins; D010455:Peptides; D010743:Phospholipids; D029867:Xenopus Proteins; C101695:alanine(19)-magainin 2 amide; C053301:magainin 2 peptide, Xenopus