title: Preferential binding of Inorganic Mercury to specific lipid classes and its competition with Cadmium.
abstract: Upon uptake of Hg and Cd into living systems, possible targets for metal induced toxicity include the membranes surrounding nervous, cardiovascular and renal cells. To further our understanding of the interactions of Hg and Cd with different lipid structures under physiologically relevant chloride and pH conditions (100 mM NaCl pH 7.4), we used fluorescence spectroscopy and dynamic light scattering to monitor changes in membrane fluidity and phase transition and liposome size. The metal effects were studied on zwitterionic, cationic and anionic lipids to elucidate electrostatically driven metal-lipid interactions. The effect of Hg-catalyzed cleavage of the vinyl ether bond in plasmalogens on these aforementioned properties was studied in addition to a thermodynamic characterization of this interaction by Isothermal Titration Calorimetry. The negatively charged Hg-chloride complexes formed under our experimental conditions induce membrane rigidity in membranes containing cationic lipids and plasmalogens while this effect is heavily reduced and entirely absent with zwitterionic and anionic lipids respectively. The KDfor the interaction of Hg with plasmalogen containing liposomes was between 4-30 μM. Furthermore, the presence of Cd affected the interaction of Hg with plasmalogen when negatively charged PS was also present. In this case, even the order of the metal addition was important.
authors.affiliation: Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Evan
authors.initials: E
authors.lastname: Kerek
authors.affiliation: Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Hassanin
authors.affiliation: Department of Chemistry, McGill University, Montréal, Québec, H3A 0B8, Canada.
authors.forename: Wenzhou
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada. Electronic address: eprenner@ucalgary.ca.
authors.forename: Elmar J
authors.initials: EJ
authors.lastname: Prenner
mesh_terms: D001667:Binding, Competitive; D002104:Cadmium / Q000737:chemistry*; D002151:Calorimetry; D008055:Lipids / Q000737:chemistry*; D008628:Mercury / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D008055:Lipids; D002104:Cadmium; D008628:Mercury
keywords: Cationic Lipids, Laurdan, Isothermal Titration Calorimetry; Heavy metals; Metal Membrane Interactions; Speciation