Oligomerization Alters Binding Affinity Between Amyloid Beta and a Modulator of Peptide Aggregation

Area of Science:

• Biochemistry
• Neuroscience
• Materials Science

Background:

• Soluble amyloid beta (Aβ) oligomers are key drivers of Alzheimer's disease (AD) pathogenesis.
• A previously developed pyrroline-nitroxyl fluorene compound (SLF) demonstrates efficacy in blocking Aβ toxicity.

Purpose of the Study:

• To quantify the binding kinetics and inhibitory effects of SLF on Aβ self-association using a label-free, real-time method.
• To elucidate the mechanism by which SLF inhibits Aβ toxicity and aggregation.
• To establish a generalizable method for analyzing protein aggregation.

Main Methods:

• Multi-parametric surface plasmon resonance (MP-SPR) for label-free, real-time quantification of SLF-Aβ interactions.
• Kinetic analysis of SLF binding to various Aβ oligomeric states.
• Molecular docking and molecular dynamics simulations to model SLF-Aβ interactions.

Main Results:

• MP-SPR successfully quantified SLF binding and its effect on Aβ self-association in real-time.
• Distinct binding affinities were observed: sub-nanomolar for Aβ monomers/dimers (non-specific) and ~100 μM for oligomeric Aβ.
• In silico modeling corroborated MP-SPR findings, providing insights into SLF-Aβ interaction mechanisms.

Conclusions:

• SLF exhibits differential binding affinities depending on the Aβ oligomeric state, explaining its inhibitory mechanism.
• MP-SPR, combined with computational modeling, offers a robust platform for studying protein-ligand interactions and aggregation processes.
• This study presents a novel, generalizable methodology for investigating the dynamics of protein aggregation relevant to neurodegenerative diseases.