title: Phospholipid lateral diffusion in phosphatidylcholine-sphingomyelin-cholesterol monolayers; effects of oxidatively truncated phosphatidylcholines.
abstract: Oxidative stress is involved in a number of pathological conditions and the generated oxidatively modified lipids influence membrane properties and functions, including lipid-protein interactions and cellular signaling. Brewster angle microscopy demonstrated oxidatively truncated phosphatidylcholines to promote phase separation in monolayers of 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphocholine (POPC), sphingomyelin (SM) and cholesterol (Chol). More specifically, 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC), was found to increase the miscibility transition pressure of the SM/Chol-phase. Lateral diffusion of lipids is influenced by a variety of membrane properties, thus making it a sensitive parameter to observe the coexistence of different lipid phases, for instance. The dependence on lipid lateral packing of the lateral diffusion of fluorophore-containing phospholipid analogs was investigated in Langmuir monolayers composed of POPC, SM, and Chol and additionally containing oxidatively truncated phosphatidylcholines, using fluorescence correlation spectroscopy (FCS). To our knowledge, these are the first FCS results on miscibility transition in ternary lipid monolayers, confirming previous results obtained using Brewster angle microscopy on such lipid monolayers. Wide-field fluorescence microscopy was additionally employed to verify the transition, i.e. the loss and reformation of SM/Chol domains.
authors.affiliation: Helsinki Biophysics & Biomembrane Group, Department of Biomedical Engineering and Computational Science, School of Science, Aalto University, Espoo, Finland.
authors.forename: Petteri
authors.initials: P
authors.lastname: Parkkila
authors.affiliation: J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 2155/3, 182 23 Prague 8, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Stefl
authors.affiliation: J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 2155/3, 182 23 Prague 8, Czech Republic.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Olżyńska
authors.affiliation: J. Heyrovský Institute of Physical Chemistry of the Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 2155/3, 182 23 Prague 8, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Hof
authors.affiliation: Helsinki Biophysics & Biomembrane Group, Department of Biomedical Engineering and Computational Science, School of Science, Aalto University, Espoo, Finland. Electronic address: paavo.kinnunen@aalto.fi.
authors.forename: Paavo K J
authors.initials: PK
authors.lastname: Kinnunen
mesh_terms: D000465:Algorithms; D002784:Cholesterol / Q000737:chemistry*; D004058:Diffusion; D008853:Microscopy / Q000379:methods; D008956:Models, Chemical; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010713:Phosphatidylcholines / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry*; D013109:Sphingomyelins / Q000737:chemistry*; D053835:Unilamellar Liposomes / Q000737:chemistry*
chemical_list: D010713:Phosphatidylcholines; D010743:Phospholipids; D013109:Sphingomyelins; D053835:Unilamellar Liposomes; D002784:Cholesterol; C028694:1-palmitoyl-2-oleoylphosphatidylcholine
keywords: Fluorescence correlation spectroscopy; Langmuir monolayers; Lateral diffusion; Liquid ordered phase; Oxidatively truncated phosphatidylcholines