Orientational alignment of amyloidogenic proteins in pre-aggregated solutions.

In the present study we combine dielectric relaxation spectroscopy with generalized Born simulations to explore the role of orientational order for protein aggregation in solutions of bovine pancreatic insulin at various pH conditions. Under aggregation-prone conditions at low pH, insulin monomers prefer antiparallel dipole alignments, which are consistent with the orientation of the monomeric subunits in the dimer structure. This alignment is also true for two dimers, suggesting that already at moderate protein concentrations the species assemble in equilibrium clusters, in which the molecules adopt preferred orientations also found for the protomers of the corresponding oligomers.

Hydration dynamics of water near an amphiphilic model peptide at low hydration levels: a dielectric relaxation study.

A dielectric relaxation study of aqueous solutions of the amphiphilic model peptide N-acetyl-leucine amide (NALA) at 298 K over a wide range of hydration levels is presented. The experiments range from states where water builds up several hydration layers to states where single water molecules or small water clusters are shared by several NALA molecules. The dielectric spectra reveal two modes on the 10 and 100 ps timescales.

The dielectric response of room-temperature ionic liquids: effect of cation variation.

In continuation of recent work on the dielectric response of imidazolium-based ionic liquids (ILs) (J. Phys. Chem.