Biophysical characterization as a tool to predict amyloidogenic and toxic properties of amyloid‐β42 peptides

Abstract

Amyloid‐β42 (Aβ42) peptides are central to the amyloid pathology in Alzheimer's disease (AD). As biological mimetics, properties of synthetic Aβ peptides usually vary between vendors and batches, thus impacting the reproducibility of experimental studies. Here, we tested recombinantly expressed Aβ42 (Asp1 to Ala42) against synthetic Aβ42 from different suppliers using matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS), circular dichroism (CD) spectroscopy, thioflavin T aggregation, surface plasmon resonance, and MTT cell viability assays. Overall, our recombinant Aβ42 provided a reproducible mimetic of desired properties. Across experimental approaches, the combined detection of Aβ42 dimers and random coil to β‐sheet transition only correlated with aggregation‐prone and cytotoxic peptides. Conclusively, combining MALDI‐MS with CD appears to provide a rapid, reliable means to predict the ‘bioactivity’ of Aβ42.

Aggregation of the Amyloid-β Peptide (Aβ40) within Condensates Generated through Liquid-Liquid Phase Separation

“…E. coli cells were induced at an optical density (OD) of 0.8 using 1 mM isopropyl β-D-1-thiogalactopyranoside (IPTG). The Aβ40 variants were subsequently purified in 50 mM Tris-HCl pH 7.4 using a previously established protocol to achieve consistent properties (40, 41). All Aβ40 was aliquoted, flash-frozen in liquid nitrogen, lyophilised, and stored at -80 °C.…”