Coordination forces between lipid bilayers produced by Ca+2 complexes

M.A. FRIAS; M. BALDUT; F. SERRESE; A. L., OÑA CEVOLI ; E.A. DISALVO

Anglet_Biarritz

Congreso; 7e Congres de Lipidomique; 2010

Groupe d'étude et de recherche en lipidomique

Attractive forces usually invoked to take place in the membrane-membrane contact in aggregation are hydrogen bonding cross-linkings and hydrophobic interactions between opposing surfaces. However, little is known in relation to the presence of non electrostatic forces in the membrane-membrane interaction. In this work, we have analyzed the formation of aggregates between adjacent vesicles mediated by ions that can stabilize a complex via coordination forces. These forces are non electrostatic interactions in which geometry and the polarizability of the ligands play an important role. One example of these aggregates are those formed between sonicated phosphatidylcholine vesicles promoted by ferricyanide in the presence of Ca2+. Similar anions of a larger charge such as ferrocyanide are unable to produce aggregation in the same conditions which reflects that electrostatic forces are not responsible (Bakas Disalvo, 1988). On the base of these previous results we have studied the stoichiometry and the mechanisms of formation of the aggregates using light sca#ering and surface potential measures in Egg phosphatidylcholine (eggPC) and dipalmitoylphosphatidylcholine (DPPC).