title: Comparison of phosphatidylcholine vesicle properties related to geometrical isomerism.
abstract: Glycerophosphatidylcholine containing trans-unsaturated fatty acid residues was prepared by reaction of the corresponding naturally occurring cis lipid with photochemically generated thiyl radicals. This modified lipid was chosen as the simplest model for gaining some insights of the complex scenario of membrane formation, in connection with the role of lipid geometry and the predominance of cis lipids in eukaryotic cells. The critical aggregation concentration for the spontaneous formation of vesicles was determined for cis and trans isomers with cis-parinaric acid used as a fluorescent probe and it was found to be similar for both lipids. Vesicle dimensions were investigated by light scattering and electron microscopy, and the type of fatty acid residues influenced the vesicle diameter, with a decrease along the series cis > trans > saturated. Fluorescence measurement of dye release from trans and cis vesicles showed also a different permeability. A picture emerged of the geometrical isomer preference in cells as a process driven by natural selection during the life evolution of different organisms, both in terms of compartment dimensions and membrane functionality.
authors.affiliation: ISOF, Consiglio Nazionale delle Ricerche, Via P. Gobetti 101, 40129 Bologna, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Ferreri
authors.forename: Silvia
authors.initials: S
authors.lastname: Pierotti
authors.forename: Andrea
authors.initials: A
authors.lastname: Barbieri
authors.forename: Laura
authors.initials: L
authors.lastname: Zambonin
authors.forename: Laura
authors.initials: L
authors.lastname: Landi
authors.forename: Silvia
authors.initials: S
authors.lastname: Rasi
authors.forename: Pier Luigi
authors.initials: PL
authors.lastname: Luisi
authors.forename: Francesco
authors.initials: F
authors.lastname: Barigelletti
authors.forename: Chryssostomos
authors.initials: C
authors.lastname: Chatgilialoglu
mesh_terms: D007536:Isomerism; D008027:Light; D008968:Molecular Conformation; D010713:Phosphatidylcholines / Q000737:chemistry*; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence
chemical_list: D010713:Phosphatidylcholines