The study explores in vitro by circular dichroism and mass spectrometry the effects of pH, Cu+2 ions and sheet-breakers on the secondary structures and self-aggregation of beta-amyloid peptides [Abeta43, Abeta42 and Abeta40] of Alzheimer's disease. Within pH 5.4-7.3, more sheet structures and aggregates containing up to 11 peptide units were observed. Cu+2 ions led to oxidative degradation or aggregation depending on its concentration and time of incubation. beta-sheet breakers can reverse the self-aggregation process, suggesting their potential therapeutic use.