Driving force of binding of amyloid beta-protein to lipid bilayers.

Amyloid beta-protein (Abeta) has been reported to interact with a variety of lipid species, although the thermodynamic driving force remains unclear. We investigated the binding of Abetas labeled with the dye diethylaminocoumarin (DAC-Abetas) to lipid bilayers under various conditions. DAC-Abeta-(1-40) electrostatically bound to anionic and cationic lipids at acidic and alkaline interfacial pH, respectively. However, at neutral pH, electroneutral Abeta did not bind to these lipids, indicating little hydrophobic interaction between Abeta-(1-40) and the acyl chains of lipids. In contrast, DAC-Abeta associated with glycolipids even under electroneutral conditions. These results suggested that hydrogen-bonding as well as hydrophobic interactions with sugar groups of glycolipids drive the membrane binding of Abeta-(1-40).