Mechanism of accelerated assembly of beta-amyloid filaments into fibrils by KLVFFK(6).

Extracellular senile plaques are a central pathological feature of Alzheimer's disease. At the core of these plaques are fibrillar deposits of beta-amyloid peptide (Abeta). In vitro, Abeta spontaneously assembles into amyloid fibrils of cross-beta sheet structure. Although it was once believed that the fibrils themselves were toxic, more recent data supports the hypothesis that aggregation intermediates, rather than fully formed fibrils, are the most damaging to neuronal tissue. In previously published work, we identified several small peptides that interact with Abeta and increase its aggregation rate while decreasing its toxicity. In this work, we examined in detail the interaction between Abeta and one of these peptides. Using a mathematical model of Abeta aggregation kinetics, we show that the dominant effect of the peptide is to accelerate lateral association of Abeta filaments into fibrils.