Spontaneous incorporation of β-amyloid peptide into neutral liposomes

The β-amyloid peptide (Aβ) is the primary constituent of senile plaques, a defining feature of Alzheimer's disease. Aβ presumably exerts its neurotoxic action through an interaction with neuronal membranes. We have studied the effect of neutral liposomes (average diameter ≈ 200 nm) on the kinetics of Aβ fibrillogenesis, and on the binding of fibrillar peptide to the dye Congo Red. Our results indicate that neutral liposomes increase the time of Aβ 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 Aβ, as well as the concentration of binding sites, decreases in the presence of liposomes. Our findings suggest that Aβ partially penetrates the lipid membrane.