Effect of ferricyanide on the agregation of Ca2+containing vesicles of egg phosphatidylcholine

L.S. BAKAS ; E.A. DISALVO

BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 1988 vol. 939 p. 295 - 304

0005-2736

The titration of sonicated vesicles of egg phophatidylcholine with ferricyanide in the presence of Ca2+ results in the formation of aggregates. The turbidity increase caused by these aggregates cannot be reversed by EDTA treatment. In addition, no rearrangement of the bilayer structure has been found in this process, either measuring leakage of vesicle content or exchange of lipids among the bilayers themselves. The aggregation is dependent on the Ca2+ content of the vesicles, the outer Ca2+ and Fe(CN)63− concentration and the order of addition of Ca2+ and ferricyanide. The results can be explained by a specific adsorption of Fe(CN)63− to bilayers of sonicated vesicles, in contrast to other multivalent anions. In contrast to the stability found with sonicated vesicles, the aggregation causes a leakage of the internal solution when multilamellar liposomes are titrated with Fe(CN)63−.