Inherent Adaptivity of Alzheimer Peptides to Crowded Environments.

Amyloid β (Aβ) is the major constituent in senile plaques of Alzheimer's disease in which peptides initially undergo structural conversions to form elongated fibrils. The impact of crowding on the fibrillation pathways of Aβ and Aβ , the most common peptide isoforms are studied. PEG and Ficoll are used as model crowders to mimic a macromolecular enriched surrounding.

How Fluorescent Tags Modify Oligomer Size Distributions of the Alzheimer Peptide.

Within the complex aggregation process of amyloidogenic peptides into fibrils, early stages of aggregation play a central role and reveal fundamental properties of the underlying mechanism of aggregation. In particular, low-molecular-weight aggregates of the Alzheimer amyloid-β peptide (Aβ) have attracted increasing interest because of their role in cytotoxicity and neuronal apoptosis, typical of aggregation-related diseases. One of the main techniques used to characterize oligomeric stages is fluorescence spectroscopy.

Near wall dynamics of a spherical particle in crowded suspensions of colloidal rods - dynamic information from TIRM revisited.

We performed total internal reflection microscopy (TIRM) experiments to determine the depletion potentials between probe spheres and a flat glass wall which are induced by long and thin, rod-shaped colloids (fd-virus), and probe the spatially resolved dynamics of the probe spheres. The dynamic information from the same raw TIRM intensity time traces is extracted in three different ways: by determining the spatially averaged diffusion constant of the probe sphere normal to the wall, by measuring the position dependence of the diffusion coefficient, and by measuring the particle's local drift velocity. Up to a concentration of about 6 times the overlap concentration of the rod-like colloids, the spatially averaged diffusion coefficient and the amplitude of the depletion potential are in surprisingly good agreement with theoretical predictions in which mutual interactions between the rods are neglected, that is, where the concentration is less than the overlap concentration.