Thermal expansivity of amyloid β16–22peptides and their aggregates in water

Abstract

Temperature dependence of the volumetric and structural properties of Aβ_16–22 peptides (wild type and pathogenic forms) and their aggregates in water was studied by simulations. The intrinsic thermal expansion coefficient α_p of peptides was evaluated by taking into account the difference between the volumetric properties of hydration and bulk water. Single peptides show mainly positive values of α_p that correlates with the increasing number of intrapeptide hydrogen bonds upon heating. Negative values of α_p found for large peptide aggregates may be attributed to the shrinking of voids inside aggregates with increasing temperature or to their rubber-like elasticity. The peptide surface exposed to water becomes more hydrophobic with increasing aggregate size that appears in decreasing density of hydration water and evidences a hydrophilic character of aggregation.