Membrane insertion and orientation of polyalanine peptides: a (15)N solid-state NMR spectroscopy investigation.
Polyalanine-based peptides were prepared by solid-phase peptide synthesis, labeled with (15)N at selected sites, reconstituted into oriented phosphatidylcholine bilayers, and investigated by proton-decoupled (15)N solid-state NMR spectroscopy. The anisotropic (15)N chemical shift is a direct indicator of helix alignment with respect to the membrane normal. The in-plane to transmembrane equilibrium is the focus of this study. Time- and solvent-dependent transmembrane alignments of K(3)A(18)K(3) have been obtained, and these are stabilized when a few alanine residues are replaced with leucine. The results are discussed in the context of a model where polyalanines adopt a variety of configurations, which are interconnected by multiple equilibria. The data indicate hydrophobicity values of alanine close to zero when studied in the context of helical polypeptides (> or =24 residues) and phospholipid bilayers.
Bechinger
B
B
Max Planck Institute for Biochemistry, 82152 Martinsried, Germany. bechinger@chimie.u-strasbg.fr
D019943:Amino Acid Substitution; D001665:Binding Sites; D007930:Leucine / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008567:Membranes, Artificial; D008956:Models, Chemical; D009587:Nitrogen Isotopes / Q000737:chemistry; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D010767:Phosphorylcholine / Q000737:chemistry*
D008051:Lipid Bilayers; D008567:Membranes, Artificial; D009587:Nitrogen Isotopes; D009842:Oligopeptides; D010455:Peptides; D010767:Phosphorylcholine; C019529:polyalanine; D007930:Leucine