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Updated: Jul 10, 2026

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Rapid Generation of Amyloid from Native Proteins In vitro
Published on: December 5, 2013
The geometry of alpha-sheet: Implications for its possible function as amyloid precursor in proteins
Steven Hayward1, E James Milner-White
1School of Computing Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom. sjh@cmp.uea.ac.uk
Proteins
|October 25, 2007
Summary
Alpha-sheet structures, key to amyloid formation, are helical and untwisted, facilitating larger, more stable stacks than beta-sheets. These "mirror" structures offer insights into protein aggregation.
Area of Science:
- Biophysics
- Structural Biology
- Computational Chemistry
Background:
- Alpha-sheet structures are implicated as the primary component of prefibrillar intermediates in amyloid formation.
- Understanding the precise helical parameters of alpha-sheet strands is crucial for elucidating amyloidogenesis mechanisms.
Purpose of the Study:
- To calculate the helical parameters of the alpha-sheet strand.
- To investigate the relationship between alpha-sheet structures and a class of conformations termed "mirror" structures.
- To compare the stacking potential of alpha-sheets with native beta-sheets.
Main Methods:
- Molecular dynamics simulations to obtain average main-chain dihedral angles.
- Calculation of helical parameters including diameter, residue count, and rise per turn.
- Analysis of structural relationships and conformational properties of mirror structures.
Main Results:
- The alpha-sheet strand forms an almost linear, right-handed helix (approx. 100 Å diameter, 100 residues, 30 Å rise/turn).
- Strands are curved but untwisted, enabling easier stacking and formation of extensive 3D blocks compared to beta-sheets.
- Alpha-sheet structures are identified as a type of "alpha-mirror" structure, characterized by specific dihedral angle patterns and side-chain orientations.
Conclusions:
- The unique helical and stacking properties of alpha-sheets contribute to their role in amyloid formation.
- "Mirror" structures, particularly alpha-mirror, exhibit wide helical conformations (50-70 Å diameter) with gentle curvature.
- The structural characteristics of alpha-sheets suggest a greater propensity for forming large aggregates than traditional beta-sheets.
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Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining, normally used to...
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