A molecular model of the amyloid fibril

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Updated: Nov 3, 2026

Amyloid and the Cross-Beta Architecture
09:06

Amyloid and the Cross-Beta Architecture

Published on: February 13, 2026

C C Blake1, L C Serpell, M Sunde

  • 1Laboratory of Molecular Biophysics, University of Oxford, UK.

Ciba Foundation Symposium
|January 1, 1996
PubMed

Insights

Researchers studied amyloid fibrils in Met30 familial amyloidotic polyneuropathy (FAP) patients. They discovered a novel beta-sheet helix structure, potentially common to all amyloid fibrils.

Area of Science:

  • Biophysics
  • Structural Biology
  • Materials Science

Background:

  • Amyloid fibrils are associated with various human diseases, including familial amyloidotic polyneuropathy (FAP).
  • The precise ultrastructure of amyloid fibrils, particularly the arrangement of beta-strands, remains incompletely understood.
  • Met30 FAP is a specific type of hereditary amyloidosis caused by a mutation in the transthyretin gene.

Purpose of the Study:

  • To elucidate the detailed ultrastructure of amyloid fibrils from patients with Met30 FAP.
  • To determine the arrangement and conformation of beta-strands within the amyloid protofilaments.
  • To investigate if the observed fibril structure is a common feature of other amyloid types.

Main Methods:

  • High-resolution electron microscopy (EM) for ultrastructural imaging.
  • X-ray diffraction (XRD) using synchrotron radiation for structural analysis.
  • Image reconstruction techniques applied to EM data.

Main Results:

  • Met30 FAP fibrils are composed of four parallel protofilaments (50-60 Å diameter) arranged in a square around a hollow core.
  • X-ray diffraction patterns indicate protofilaments contain repeating units of 24 beta-strands forming a continuous beta-sheet helix.
  • This beta-sheet helix structure reconciles the classical cross-beta structure with stable, twisted beta-sheet conformations.

Conclusions:

  • A novel beta-sheet helix structure has been characterized as the repeating unit within Met30 FAP amyloid protofilaments.
  • This beta-sheet helix represents a stable conformation that integrates known amyloid structural features.
  • The structural similarity of other amyloid diffraction patterns suggests the beta-sheet helix may be a generic core structure for amyloid fibrils.

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