title: Effects of thallium(I) and thallium(III) on liposome membrane physical properties.
abstract: The hypothesis that thallium (Tl) interaction with membrane phospholipids could result in the alteration of membrane physical properties was investigated. Working with liposomes composed of brain phosphatidylcholine and phosphatidylserine, we found that Tl(+), Tl(3+), and Tl(OH)(3) (0.5-25 microM): (a) increased membrane surface potential, (b) decreased the fluidity of the anionic regions of the membrane, in association with an increased fluidity in the cationic regions, and (c) promoted the rearrangement of lipids through lateral phase separation. The magnitude of these effects followed the order Tl(3+), Tl(OH)(3)>Tl(+). In addition, Tl(3+) also decreased the hydration of phospholipid polar headgroups and induced membrane permeabilization. The present results show that Tl interacts with membranes inducing major alterations in the rheology of the bilayer, which could be partially responsible for the neurotoxic effects of this metal.
authors.affiliation: Department of Biological Chemistry, IQUIFIB (UBA-CONICET), School of Pharmacy and Biochemistry, University of Buenos Aires, Junín 956, C1113AAD, Buenos Aires, Argentina.
authors.forename: Marcela S
authors.initials: MS
authors.lastname: Villaverde
authors.forename: Sandra V
authors.initials: SV
authors.lastname: Verstraeten
mesh_terms: D001923:Brain Chemistry; D008081:Liposomes / Q000138:chemical synthesis / Q000737:chemistry*; D046911:Macromolecular Substances; D008560:Membrane Fluidity; D008561:Membrane Fusion; D008564:Membrane Potentials; D010539:Permeability; D010713:Phosphatidylcholines / Q000737:chemistry*; D010718:Phosphatidylserines / Q000737:chemistry*; D055672:Static Electricity; D013499:Surface Properties; D013793:Thallium / Q000737:chemistry*
chemical_list: D008081:Liposomes; D046911:Macromolecular Substances; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; D013793:Thallium