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Macromolecular crowding accelerates amyloid formation by human apolipoprotein C-II
Danny M Hatters1, Allen P Minton, Geoffrey J Howlett
1Russell Grimwade School of Biochemistry and Molecular Biology, The University of Melbourne, Victoria 3010, Australia.
The Journal of Biological Chemistry
|December 26, 2001
Summary
Inert polymers like dextran T10 accelerate human apolipoprotein C-II (apoC-II) amyloid fiber formation by increasing molecular crowding. This volume exclusion effect enhances amyloidogenesis in physiological conditions.
Area of Science:
- Biochemistry
- Biophysics
- Protein Science
Background:
- Human apolipoprotein C-II (apoC-II) is known to slowly form amyloid fibers in solution.
- Amyloid formation is implicated in various neurodegenerative diseases.
Purpose of the Study:
- To investigate the effect of inert polymers on apoC-II amyloid formation.
- To elucidate the mechanism by which polymers influence amyloidogenesis.
Main Methods:
- Turbidity measurements over time
- Thioflavin T (ThT) fluorescence assays
- Analytical ultracentrifugation
- Congo Red binding assays
Main Results:
- Dextran T10 significantly increased the rate and extent of apoC-II amyloid formation at concentrations above 20 g/liter.
- High dextran concentrations did not alter protein secondary structure, fiber morphology, or dye binding capacity.
- Analytical ultracentrifugation indicated no significant association between monomeric apoC-II and dextran.
- The observed acceleration was quantitatively explained by a nonspecific volume exclusion model.
Conclusions:
- Nonspecific volume exclusion by inert polymers can accelerate amyloid fiber formation.
- Increased macromolecular crowding in physiological fluids may enhance amyloidogenesis for various amyloidogenic proteins.