STRUCTURAL STUDY ON THE INTERACTION OF LI-BILAYERS(, CD2+ AND AL3+ IONS WITH PHOSPHOLIPID)

Phospholipids are amphiphilic molecules of biological interest as they constitute an integral part of many natural membranes under the form of bilayers. Given the structural complexity of these membranes, phosp holipid bilayers are useful model for studying how biologically releva nt chemicals affect their structures and functions. Lithium, cadmium a nd aluminum have been associated to neurological problems which have b een related to their interactions with cell membranes. In this paper, the structural effects of Li+, Cd2+ and Al3+ ions on the phospholipids dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidyletha nolamine (DMPE) are reported. These studies were carried out with diff erent concentrations of each cation by X-ray diffraction methods. The results revealed differences in their binding to both phospholipid bil ayers. Whereas the structure of DMPE was not perturbed by any of these ions to a significant extent, Cd2+ and Al3+ did interact with DMPC, d isordering its molecular arrangement. It was also found that 0.1M and higher concentrations of Al3+ had an ordering effect on DMPC bilayers.