Spontaneous incorporation of β-amyloid peptide into neutral liposomes

The beta-amyloid peptide (A beta) is the primary constituent of senile plaques, a defining feature of Alzheimer's disease. A beta presumably exerts its neurotoxic action through an interaction with neuronal membranes. We have studied the effect of neutral liposomes (average diameter approximate to 200 nm) on the kinetics of A beta fibrillogenesis, and on the binding of fibrillar peptide to the dye Congo Red. Our results indicate that neutral liposomes increase the time of A beta autoaggregation in a concentration-dependent manner. This delay is mainly due a reduction of the nucleation constant. In addition, binding studies reveal that the amount of fibrillar A beta, as well as the concentration of binding sites, decreases in the presence of liposomes. Our findings suggest that A beta partially penetrates the lipid membrane. (c) 2005 Elsevier B.V. All rights reserved.