Hydration water mobility is enhanced around tau amyloid fibers

Protein aggregation into amyloid fibers and oligomers is observed in a variety of neurodegenerative diseases. The fibers formed by the intrinsically disordered human protein tau, for instance, are one of the hallmarks of Alzheimer disease. In this work, we report on the dynamic behavior of tau hydration water, which we found to be more mobile in tau fibers than in nonaggregated tau. This increase in mobility could promote fiber formation through an increase in hydration water entropy. That hydration water is more mobile around the pathological form of tau corroborates that methodologies sensitive to the diffusion of water, such as diffusion magnetic resonance imaging, could be used to diagnose Alzheimer patients in an early stage of the disease.