Unraveling the Speciation of β-Amyloid Peptides during the Aggregation Process by Taylor Dispersion Analysis

Abstract

The aggregation mechanisms of amyloid β peptides depend on multiple intrinsic and extrinsic physico-chemical factors (e.g. peptide chain length, truncations, peptide concentration, pH, ionic strength, temperature, metal concentrations…). Due to this high number of parameters, the formation of the oligomers and their propensity to aggregate make the elucidation of this physiopathological mechanism a challenging task. From the analytical point of view, up to our knowledge, few techniques are able to quantify, in real time, the proportion and the size of the different soluble species during the aggregation process. This work aims at demonstrating the interest of modern Taylor dispersion analysis (TDA) performed in capillaries (50 µm i.d.) to unravel the speciation of β-amyloid peptides in low volume peptide samples (~100 µL) with an analysis time of ~ 3 min per run. TDA was applied to study the aggregation process of and Aβ(1-42) peptides at physiological pH and temperature, where more than 140 data points were generated with a total volume of ~1 µL over the whole aggregation study (about 0.5 µg of peptide). TDA was able the give a complete and quantitative picture of the Aβ speciation during the aggregation process, including the sizing of the oligomers and protofibrils, the consumption of the monomer, and the quantification of different early and late-formed aggregated species.

CE-ICP-MS to probe Aβ1-42/copper (II) interactions, a complementary tool to study amyloid aggregation in Alzheimer's disease

“…Based on these results, the presence of two different populations containing Aβ1-42 was assumed: one fast migrating population (µep ~ -2 x10 -8 m 2 .s -1 .V -1 ) with a large hydrodynamic radius, attributed to large oligomers, and one population migrating slower (µep ~ -1 x10 -8 m 2 .s -1 .V -1 ) with a smaller hydrodynamic radius, attributed to monomers and small oligomers. This assumption is reinforced by the data obtained by Deleanu et al 29 , who proposed possible conformations of Aβ1-42 in relation with their size determined by TDA. They found a population of monomers and small oligomers, with a mean hydrodynamic radius around 1.9 nm, and a population of larger oligomers, with a mean radius around 5.1 nm.…”

“…12 Indeed, it was postulated that A1-40 displays a different aggregation pathway, which does not lead to the formation of transient soluble oligomers. 29 Fig. 3b shows the percentage of Aβ1-42 involved in large oligomers in the soluble fraction.…”

The amyloid concentric β‐barrel hypothesis: Models of amyloid beta 42 oligomers and annular protofibrils

“…The quest to determine precise molecular mechanisms by which amyloid beta (Aβ) peptides wreak havoc on the human brain can appear hopeless. These peptides are shapeshifters; they assume countless forms that are often present simultaneously and likely have partially occupied secondary structures (see Deleanu et al 1 and Urban et al 2 for recent reviews). Numerous factors affect Aβ assemblies; for example, ions and heavy cations, lipids, concentration, time, method of isolation and preparation, location in the body, initial seed conformation, length of the peptide, and oxidation.…”

Macrocyclic Cavitand β‐Cyclodextrin Inhibits the Alcohol‐Induced Trypsin Aggregation

“…Series of sequential or parallel events (destabilization of the native structure induced by the change in temperature, pH, ionic strength, solvents, etc.) trigger the protein unfolding process which in turn manifests the aggregation of proteins [1–3] . Misfolded proteins generally lead to two major forms of anomalous aggregates: amyloid fibrils and amorphous aggregates [4] .…”

“…trigger the protein unfolding process which in turn manifests the aggregation of proteins. [1][2][3] Misfolded proteins generally lead to two major forms of anomalous aggregates: amyloid fibrils and amorphous aggregates. [4] Such aggregation often results in several neurodegenerative diseases like Alzheimer's, and Parkinson's diseases.…”