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

The aggregation behavior of the major component of Alzheimer's disease-related, amyloid peptides, Abeta-(1-40) and Abeta-(1-42), was studied in solution using dynamic light scattering. With most solvents employed, we found fibrils coexisting with oligomeric Abeta species. Pronounced differences were observed in aggregation of Abeta-(1-40) and (1-42) sequences in acetonitrile-water mixtures. Cofactors such as Zn2+ were found to induce deaggregation of Abeta 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.