Interaction between synthetic amyloid-beta-peptide (1-40) and its aggregation inhibitors studied by electrospray ionization mass spectrometry

It is generally postulated that amyloid-beta -peptides play a central role in the progressive neurodegeneration observed in Alzheimer's disease. Impor tant pathological properties of these peptides, such as neurotoxicity and r esistance to proteolytic degradation, depend on the ability of amyloid-beta -peptides to form beta -sheet structures and/or amyloid fibrils. Amyloid-b eta -peptides are known to aggregate spontaneously in vitro with the format ion of amyloid fibrils. The intervention on the amyloid-beta -peptides aggr egation process can be envisaged as an approach to stopping or slowing the progression of Alzheimer's disease. In the last few years a number of small molecules have been reported to interfere with the in vitro aggregation of amyloid-beta -peptides. Melatonin, a hormone recently found to protect neu rons against amyloid-beta -peptide toxicity, interacts with amyloid-beta -p eptide (1-40) and amyloid-beta -peptide (1-42) and inhibits the progressive formation of beta -sheet and/or amyloid fibrils. These interactions betwee n melatonin and the amyloid peptides have been demonstrated by circular dic hroism (CD) and electron microscopy for amyloid-beta -peptide (1-40) and am yloid-beta -peptide (1-42) and by nuclear magnetic resonance (NMR) spectros copy for amyloid-beta -peptide (1-40). Our electrospray ionization mass spe ctrometric (BSI-MS) studies also proved that there is a hydrophobic interac tion between amyloid-beta -peptide (1-40) and melatonin and the proteolytic investigations suggested that the interaction took place on the 29-40 amyl oid-beta -peptide segment. The wide-ranging application of these results wo uld provide further information and help in biological research. Copyright (C) 2001 John Wiley & Sons, Ltd.