Related Experiment Video
Updated: Mar 3, 2026
Characterizing Individual Protein Aggregates by Infrared Nanospectroscopy and Atomic Force Microscopy
Published on: September 12, 2019
Nucleation dynamics in amyloid-beta dimerization revealed by single-molecule fingerprinting
A K M Kafi1,2, Mathias Bogetoft Danielsen3,2, Shixi Song3
1Department of Chemistry and Biochemistry, Kent State University, Kent, OH 44242, USA.
Abstract:
The aggregation of amyloid-beta peptides ( or ) is closely related to the pathology of Alzheimer's disease (AD). Soluble oligomers that appear during aggregation are primary neurotoxic species; however, their misfolding kinetics have yet to be determined. Here, we report a bottom-up construction of parallel and antiparallel dimers, the first oligomers formed during aggregation. We apply single-molecule mechanical unfolding in optical tweezers to investigate the dynamic structural evolution of these dimers at the single-amino-acid resolution. We observe three intermediates during the association and dissociation of individual dimers, with the diphenylalanine dimer having the highest formation probability. Our single-molecule fingerprinting method reveals that a known aggregation inhibitor, rosmarinic acid, can reduce dimerization by binding to the site. We anticipate that the molecular tool innovated in our study is extensible to investigating other amyloid aggregations responsible for a myriad of neurodegenerative diseases.
Insights
Researchers constructed amyloid-beta (Aβ) dimers, the initial oligomers in Alzheimer's disease (AD) pathology. Using single-molecule optical tweezers, they identified key intermediates and found rosmarinic acid inhibits Aβ dimerization.
Area of Science:
- Biophysics
- Neurodegenerative Diseases
- Molecular Biology
Background:
- Amyloid-beta (Aβ) peptide aggregation is central to Alzheimer's disease (AD) pathology.
- Soluble Aβ oligomers are the primary neurotoxic species, but their formation kinetics are poorly understood.
- Understanding the earliest stages of Aβ aggregation is crucial for developing therapeutic strategies.
Purpose of the Study:
- To construct and characterize the first oligomers formed during Aβ aggregation: parallel and antiparallel Aβ(1-40) dimers.
- To investigate the dynamic structural evolution and misfolding kinetics of these dimers at single-amino-acid resolution.
- To explore the inhibitory effect of rosmarinic acid on Aβ(1-40) dimerization.
Main Methods:
- Bottom-up construction of Aβ(1-40) dimers.
- Single-molecule mechanical unfolding using optical tweezers.
- Single-molecule fingerprinting to identify molecular interactions.
Main Results:
- Successfully constructed parallel and antiparallel Aβ(1-40) dimers.
- Observed three intermediates during dimer association and dissociation, with the diphenylalanine (Aβ(19-20)) dimer showing the highest formation probability.
- Demonstrated that rosmarinic acid inhibits Aβ(1-40) dimerization by binding to the Aβ(19-20) site.
Conclusions:
- The study provides the first detailed characterization of Aβ dimer formation kinetics.
- The developed single-molecule tool is effective for studying amyloid aggregation dynamics.
- Rosmarinic acid shows potential as an inhibitor of early-stage Aβ aggregation relevant to Alzheimer's disease.
More Related Videos
07:56Utilizing Time-Resolved Protein-Induced Fluorescence Enhancement to Identify Stable Local Conformations One α-Synuclein Monomer at a Time
Published on: May 30, 2021
08:48High-Resolution Neutron Spectroscopy to Study Picosecond-Nanosecond Dynamics of Proteins and Hydration Water
Published on: April 28, 2022
