Hg2+ and Cd2+ interact differently with biomimetic erythrocyte membranes |
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Authors: | Mary Trang Le Jürgen Gailer Elmar J. Prenner |
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Affiliation: | (1) Department of Biological Sciences, University of Calgary, 2500 University Drive, Calgary, AB, Canada, T2N 1N4;(2) Department of Chemistry and Environmental Science Program, University of Calgary, 2500 University Drive, Calgary, AB, Canada, T2N 1N4 |
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Abstract: | In order to characterize the potentially deleterious effects of toxic Hg2+ and Cd2+ on lipid membranes, we have studied their binding to liposomes whose composition mimicked erythrocyte membranes. Fluorescence spectroscopy utilizing the concentration dependent quenching of Phen Green™ SK by Hg2+ and Cd2+ was found to be a sensitive tool to probe these interactions at metal concentrations ≤1 μM. We have systematically developed a metal binding affinity assay to screen for the interactions of Hg2+ or Cd2+ with certain lipid classes. A biomimetic liposome system was developed that contained four major lipid classes of erythrocyte membranes (zwitterionic lipids: phosphatidylcholine and phosphatidylethanolamine; negatively charged: phosphatidylserine and neutral: cholesterol). In contrast to Hg2+, which preferentially bound to the negatively charged phosphatidylserine compared to the zwitterionic components, Cd2+ bound stronger to the two zwitterionic lipids. Thus, the observed distinct differences in the binding affinity of Hg2+ and Cd2+ for certain lipid classes together with their known effects on membrane properties represent an important first step toward a better understanding the role of these interactions in the chronic toxicity of these metals. |
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Keywords: | Toxic metals Hg2+ Cd2+ Liposomes Model systems Membranes Lipids Erythrocytes Fluorescence spectroscopy |
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