Peptid-tethered bilayer lipid membranes and their interaction with Amyloid beta-peptide.

The Amyloid peptide (Ass), a normal constituent of neuronal and non-neuronal cells, has been shown to be a major component of the extracellular plaque of Alzheimer disease (AD). The interaction of Ass peptides with the lipid matrix of neuronal cell membranes plays an important role in the pathogenesis of AD. In this study, we have developed peptide-tethered artificial lipid membranes by the Langmuir-Blodgett and Langmuir-Schaefer methods. Anti-Ass40-mAb labeled with a fluorophore was used to probe Ass40 binding to these model membranes. Systematic studies on the antibody or Ass-membrane interactions were carried out by surface plasmon field-enhanced fluorescence spectroscopy. It was found that the Ass adsorption is critically depending on the lipid composition of the membranes, with Ass specifically binding to membranes containing sphingomyelin. Further, this preferential adsorption was markedly amplified by the addition of sterols (cholesterol or 25-OH-Chol).