Amylin and Amyloid beta: Structure, Membrane Interaction and Cellular Entry Mechanisms

Amyloid beta (Aβ) oligomer is thought to be the major toxic species for the Alzheimer’s disease. But it is still unknown whether different regions play specific roles in the multi-step toxicity pathway. Here, we have decoupled the functionality of the core region (residues 18-35) vs the N- terminal (1-9) in terms of affinity towards membrane, entry and spatial distribution within neuronal cells. Using temperature dependence of cell entry, we probe the underlying mechanism of cell entry is active or passive. We also probe the role of membrane potential in mediating membrane affinity, by artificially creating a transmembrane potential in small unilammelar vesicles.

Amylin is another amyloidogenic peptide, which is responsible for type-II diabetes. For amylin too, the smaller oligomeric species is the major toxic species. Here, to understand the relation between structure and function, we have probed the secondary structural changes between the oligomers and fibrils of amylin using Raman and IR spectroscopy. We also perturb the lone di-sulphide linkage in this peptide to understand its role in membrane binding and toxicity.