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Tertiary contact formation in alpha-synuclein probed by electron transfer.
Jennifer C Lee1, Harry B Gray, Jay R Winkler
1Beckman Institute, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125-7400, USA. lee@caltech.edu
Journal of the American Chemical Society
|November 25, 2005
Summary
Tertiary contact formation in alpha-synuclein, implicated in Parkinson's disease, was studied using electron transfer kinetics. Faster contact times were observed with shorter loop sizes, revealing insights into protein folding dynamics.
Area of Science:
- Biochemistry
- Biophysics
- Neuroscience
Background:
- Alpha-synuclein is a natively unfolded protein associated with Parkinson's disease.
- Understanding its tertiary contact formation is crucial for elucidating disease mechanisms.
Purpose of the Study:
- To investigate the relationship between loop size and tertiary contact formation rates in alpha-synuclein variants.
- To measure electron transfer kinetics between tryptophan and 3-nitro-tyrosine in different alpha-synuclein constructs.
Main Methods:
- Utilized electron donor (tryptophan triplet excited state) and acceptor (3-nitro-tyrosine) systems.
- Measured reaction rates across six variants with loop sizes ranging from 15 to 132 residues.
- Analyzed kinetics using simultaneous fits of electron and energy transfer data.
Main Results:
- Electron transfer rates decreased as loop size increased.
- Fastest contact time was 140 ns (N-terminal pair), slowest was 1.2 µs (N- to C-terminal pair).
- Extracted diffusion coefficients between approximately 2 x 10^-6 and 10^-5 cm^2 s^-1.
Conclusions:
- Loop size significantly influences tertiary contact formation rates in alpha-synuclein.
- Findings provide insights into the dynamics and folding of natively unfolded proteins.
- This research contributes to understanding the structural basis of Parkinson's disease pathogenesis.