Aggregation processes in beta-amyloid peptides: effects of molecular chaperons

Several neurodegenerative pathologies, like Parkinson's, Hungtington's and Alzheimer's diseases, are related to the formation of small peptides aggregates, which amyloid fibrils originate from. Understanding the molecular mechanisms responsible for these processes can, therefore, contribute to clarify the origin and, hopefully, to control the development of the afore mentioned diseases. Here we report the results of an in vitro study aiming to affect the aggregation kinetic of 1-42 and 1-40 beta-amyloid peptides by means of an endogenous chaperone-like protein (alpha-crystallin) and an exogenous polycyclic aromatic pigment (hypericin) that can perturb the aggregation process through stacking interactions with the peptides aromatic residues. Because of the well known problems in getting reproducible and reliable results, particular attention has been devoted to carefully check the preparation procedures of the samples. The effects of both alpha-crystallin and hypericin on the self-assembly process have been examined at different times of the aggregation kinetics. The results are discussed in relation with the involvement of different molecular structures in the amyloid fibrillation phenomenon.