The impact of amyloid beta assembly on membrane conformational stability and dynamics

Alzheimer’s disease (AD) is a neurodegenerative disorder that cause irreversible loss of neurons. Despite it is the most common form of dementia, the mechanism by which AD develops is still unclear. One of the hypothesis is based on the aggregation and the accumulation of amyloid β (Aβ) peptide around neuronal cells. Aβ peptide is present in two different form: Aβ40 and Aβ42. The first one is the most abundant in amyloid plaques and can assumes only a U-shaped structure, the second one is the most toxic and can assumes both U- and S- shaped structure. Recent studies demonstrate that the S-shaped form is more stable and compact. Amyloid peptide aggregates interact with the cell membrane producing toxic effects on the normal cell functions and activities. In particular, amyloid peptide are able to disrupt the cell membrane causing ionic homeostasis, membrane leakage and penetration of small molecules and ions inside the cell. Small assemblies, especially small oligomers, seem to mostly destabilize the membrane increasing its rigidity. Molecular Dynamics simulations permit to clarify the mechanism underlying Aβ aggregation and their membrane interaction. The present study has the purpose to study the effect of both ordered and disordered Aβ11-42 pentamer inserted in POPC bilayer.