Detergent-like interaction of Congo red with the amyloid beta peptide.

Accumulating evidence links prefibrillar oligomeric species of the amyloid beta peptide (Abeta) to cellular toxicity in Alzheimer's disease, potentially via disruption of biological membranes. Congo red (CR) affects protein aggregation. It is known to self-associate into micelle-like assemblies but still reduces the toxicity of Abeta aggregates in cell cultures and model organisms. We show here that CR interacts with Abeta(1-40) in a manner similar to that of anionic detergents. Although CR promotes beta sheet formation and peptide aggregation, it may also solubilize toxic protein species, making them less harmful to critical cellular components and thereby reducing amyloid toxicity.