title: Bicelle membranes and their use for hydrophobic peptide studies by circular dichroism and solid state NMR.
abstract: Mixtures of dicaproyl- (DC), dimyristoyl- (DM) and 1-tetradecanoyl-2-biphenylbutanoyl-(TBB) phosphatidylcholine (PC) in water produce bicelle membranes that are oriented by magnetic fields. DMPC/DCPC systems orient such that their membrane plane is parallel to the magnetic field, whereas for TBBPC/DCPC, the plane is perpendicular to the field. Partial temperature-composition-hydration diagrams are established using solid-state 31P-NMR. DMPC/DCPC bicelles exist on a large range of composition but on a narrow temperature domain (25-45 degrees C). At converse, TBBPC/DCPC form bicelles on a narrow compositional range but over a large temperature span (10-70 degrees C). The TBBPC/DCPC bicelles are shown to be a very powerful potential tool to study the orientation of hydrophobic helices in membranes using wide line 15N-NMR. The DMPC/DCPC system that undergoes a micelle-to-bicelle transition on going from 10 degrees C to 40 degrees C may be used with circular dichroism to study the state of association of hydrophobic helices within the membrane. Results suggest that the transmembrane fragment of the neu/erbB-2 receptor is monomeric in micellar medium and dimeric/multimeric in bicelle membranes.
authors.affiliation: UMR5144 MOBIOS, CNRS-UBx1, Institut Européen de Chimie et Biologie, 33607 Pessac, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Loudet
authors.forename: Lucie
authors.initials: L
authors.lastname: Khemtémourian
authors.forename: Fabien
authors.initials: F
authors.lastname: Aussenac
authors.forename: Stéphane
authors.initials: S
authors.lastname: Gineste
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Achard
authors.forename: Erick J
authors.initials: EJ
authors.lastname: Dufourc
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004134:Dimyristoylphosphatidylcholine; D057927:Hydrophobic and Hydrophilic Interactions; D008081:Liposomes; D009682:Magnetic Resonance Spectroscopy; D008567:Membranes, Artificial; D008823:Micelles; D008969:Molecular Sequence Data; D009587:Nitrogen Isotopes; D010446:Peptide Fragments / Q000737:chemistry*; D010713:Phosphatidylcholines; D010759:Phosphorus Isotopes; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000737:chemistry; D013696:Temperature; D014867:Water
chemical_list: D004134:Dimyristoylphosphatidylcholine; D008081:Liposomes; D008567:Membranes, Artificial; D008823:Micelles; D009587:Nitrogen Isotopes; D010446:Peptide Fragments; D010713:Phosphatidylcholines; D010759:Phosphorus Isotopes; D018719:Erb-b2 Receptor Tyrosine Kinases; D014867:Water; C015132:1,2-didecanoylphosphatidylcholine