Hg2+ and Cd2+ interact differently with biomimetic erythrocyte membranes
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- Le, M.T., Gailer, J. & Prenner, E.J. Biometals (2009) 22: 261. doi:10.1007/s10534-008-9162-7
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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.
KeywordsToxic metalsHg2+Cd2+LiposomesModel systemsMembranesLipidsErythrocytesFluorescence spectroscopy
Phen Green™ SK