SANS study of Amyloid ?1-40: Unfolded monomers in DMSO, multidimensional aggregates in water medium

Neurodegenerative diseases such as Alzheimer's are characterized by neuritic plaques throughout the brain gray matter, associated with neurofibrillary tangles and neuron loss. These plaques are formed by abnormal aggregation of amyloid beta (A?) peptide into insoluble fibrils. In the present work we study the A?1-40 peptide in the three aggregations states - monomers, oligomers and fibrils - via small angle neutron scattering (SANS) technique. The size of the three forms as well as their fractal nature are investigated at physiologic conditions. Our results evidence that the A?1-40 peptide has a good aggregation capability but can also adopt an unfolded conformation in particular conditions, as for example, when incubated in DMSO.