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Rapid Generation of Amyloid from Native Proteins In vitro
Published on: December 5, 2013
Amyloid formation may involve alpha- to beta sheet interconversion via peptide plane flipping.
James E Milner-White1, James D Watson, Guoying Qi
1Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, United Kingdom. j.milner-white@bio.gla.ac.uk
Structure (London, England : 1993)
|September 12, 2006
Summary
Toxic amyloid prefibrillar intermediates may form via alpha-sheet to beta-sheet conversion. This transition occurs through peptide plane flipping, a common mechanism observed in protein structures.
Area of Science:
- Biochemistry
- Structural Biology
- Protein Folding
Background:
- Amyloid toxicity is linked to soluble prefibrillar intermediates, not mature fibers.
- A proposed mechanism involves alpha-sheet precursors converting to beta-sheets via peptide plane flipping.
Purpose of the Study:
- To investigate the mechanism of alpha-sheet to beta-sheet conversion in amyloid formation.
- To provide evidence for peptide plane flipping as a direct interconversion pathway.
Main Methods:
- Molecular dynamics simulations were used to propose the alpha-sheet precursor model.
- A comprehensive search of protein crystal structures was conducted to identify peptide plane flips.
Main Results:
- The study demonstrates that alpha- to beta-sheet transitions can occur via flipping of alternate peptide planes (alphaRalphaL<-->betabeta).
- These flips were found to be common, present in 8.5% of protein families analyzed.
- Analysis of the 'alphaL' conformation revealed restricted movements in flanking peptide planes, consistent with hydrogen bonding constraints.
Conclusions:
- Peptide plane flipping provides a direct mechanism for alpha- to beta-sheet interconversion.
- This finding supports the role of soluble intermediates in amyloid toxicity and offers insights into protein structural dynamics.
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