Potentiation of beta-folding of β-amyloid peptide 25-35 by aluminum salts

The formation of the beta pleated configuration of the amyloid peptide fragment 25-35 in aqueous solution, has been studied using thioflavin-T fluorescence as an indicator of such folding. Both phosphate and adenosine triphosphate (ATP) enhance the formation of aggregated beta-sheets. This phosphate-induced aggregation is greater in the presence of aluminum sulfate in a dose dependent manner. In the absence of ATP or phosphate, aluminum salts do not promote aggregation. It is proposed that a particulate aluminum phosphate complex may form critical nuclei upon whose surface the amyloid peptide can change its configuration. This capacity for seeding may be a relevant factor in the formation of insoluble proteinaceous materials such as amyloid plaques and neurofibrillary tangles found in Alzheimer's disease. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.