Aggregation of Aβ Alzheimer's disease-related peptide studied by dynamic light scattering

The aggregation behavior of the major component of Alzheimer's disease-related, amyloid peptides, A beta-(1-40) and A beta-(1-42), was studied in solution using dynamic light scattering. With most solvents employed, we found fibrils coexisting with oligomeric A beta species. Pronounced differences were observed in aggregation of A beta-(1-40) and (1-42) sequences in acetonitrile-water mixtures. Cofactors such as Zn2+ were found to induce deaggregation of A beta instead of aggregation. The results indicated that the initial state of the peptide immediately after synthesis is rather poorly defined. Using freezing instead of lyophilization after the final peptide synthesis step, may partially relieve these problems.