Interaction of A beta peptide (1-40) with amino acid aluminium complexes: relevance to Alzheimer's disease

A beta (39-43 aminoacid residues) is the principal peptide component of amy loid deposits in Alzheimer's disease (AD). A beta peptide is derived from t he amyloid precursor protein (APP) in which mutations give rise to many for ms of familial AD. Aluminium is reported to play a key role in inducing con formational change in the synthetic beta-amyloid peptide (1-40)from alpha-h elix to beta-pleated sheet, leading to aggregation and fibrillar formation. We have studied the interaction of amino acid-Al complexes such as D-Asp-A l and L-Glu-Al with A beta(1-40) in TFE/buffer (70% TFE and 30% H2O v/v pH 6.7) mixture using CD spectroscopy. The interaction of either of these amin o acid complexes with A beta(1-40) results in loss of alpha-helical content and the peptide is more unstructured compared to free Al3+ in the solution . Our data strongly support the idea, that the Al3+ in the form of aminoaci d-Al complexes is more effective in inducing random coil conformation in th e A beta peptide than the free Al3+ present in the solution.