Related Experiment Video
Updated: Jul 8, 2026
07:56
Utilizing Time-Resolved Protein-Induced Fluorescence Enhancement to Identify Stable Local Conformations One α-Synuclein Monomer at a Time
Published on: May 30, 2021
Conformational equilibria in monomeric alpha-synuclein at the single-molecule level
Massimo Sandal1, Francesco Valle, Isabella Tessari
1Department of Biochemistry G. Moruzzi, University of Bologna, Bologna, Italy.
Plos Biology
|January 18, 2008
Summary
Single-molecule force spectroscopy reveals human alpha-synuclein (alphaSyn) conformational heterogeneity. Beta-like structures, linked to Parkinson
Area of Science:
- Biophysics
- Neuroscience
- Protein Chemistry
Background:
- Human alpha-synuclein (alphaSyn) aggregation into amyloid fibrils is central to Parkinson disease pathology.
- Understanding early aggregation intermediates is crucial for deciphering molecular mechanisms.
- Traditional bulk methods provide ensemble-averaged data, masking conformational complexity.
Purpose of the Study:
- To investigate the conformational equilibrium of monomeric human alphaSyn at the single-molecule level.
- To characterize the heterogeneity of alphaSyn conformations and their relation to aggregation propensity.
- To establish a single-molecule tool for assessing factors influencing alphaSyn conformational states.
Main Methods:
- Application of atomic force microscopy (AFM)-based single-molecule mechanical unfolding.
- Direct observation and quantification of individual alphaSyn monomer conformations.
- Analysis of conformational changes under conditions promoting aggregation (Cu2+, A30P mutation, high ionic strength).
Main Results:
- Directly observed and quantified three main classes of monomeric alphaSyn conformations, including disordered and beta-like structures.
- Found a significant increase in beta-like structures under aggregation-promoting conditions.
- Demonstrated that the pathogenic A30P mutation and specific environmental factors enhance beta-like conformer populations.
Conclusions:
- Presented the first evidence of a conformational equilibrium controlling monomeric alphaSyn populations, specifically beta-like conformers.
- Established a positive correlation between beta-like conformer abundance and conditions known to promote alphaSyn aggregation.
- Introduced a novel single-molecule methodology to probe protein conformational landscapes and test therapeutic strategies for Parkinson disease.
More Related Videos
Related Concept Videos
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
01:22Protein Folding
Overview
01:25Protein Folding
Proteins are chains of amino acids linked together by peptide bonds. Upon synthesis, a protein folds into a three-dimensional conformation, critical to its biological function. Interactions between its constituent amino acids guide protein folding, and hence the protein structure is primarily dependent on its amino acid sequence.
Protein Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
Protein Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
01:15¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.
03:03Amyloid Fibrils
Amyloid fibrils are aggregates of misfolded proteins. Under most circumstances, misfolded proteins are either refolded by chaperone proteins or degraded by the proteasome. However, in the case of a mutation or a disease, these proteins can accumulate to form large clusters and often further assemble to form elongated fibers, called fibrils.
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...
01:58Cooperative Allosteric Transitions
Cooperative allosteric transitions can occur in multimeric proteins, where each subunit of the protein has its own ligand-binding site. When a ligand binds to any of these subunits, it triggers a conformational change that affects the binding sites in the other subunits; this can change the affinity of the other sites for their respective ligands. The ability of the protein to change the shape of its binding site is attributed to the presence of a mix of flexible and stable segments in the...