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Updated: Jun 8, 2026

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Amyloid structure and assembly: insights from scanning transmission electron microscopy
Claire Goldsbury1, Ulrich Baxa, Martha N Simon
1The Brain and Mind Research Institute, University of Sydney, NSW 2006, Australia.
Abstract:
Amyloid fibrils are filamentous protein aggregates implicated in several common diseases such as Alzheimer's disease and type II diabetes. Similar structures are also the molecular principle of the infectious spongiform encephalopathies such as Creutzfeldt-Jakob disease in humans, scrapie in sheep, and of the so-called yeast prions, inherited non-chromosomal elements found in yeast and fungi. Scanning transmission electron microscopy (STEM) is often used to delineate the assembly mechanism and structural properties of amyloid aggregates. In this review we consider specifically contributions and limitations of STEM for the investigation of amyloid assembly pathways, fibril polymorphisms and structural models of amyloid fibrils. This type of microscopy provides the only method to directly measure the mass-per-length (MPL) of individual filaments. Made on both in vitro assembled and ex vivo samples, STEM mass measurements have illuminated the hierarchical relationships between amyloid fibrils and revealed that polymorphic fibrils and various globular oligomers can assemble simultaneously from a single polypeptide. The MPLs also impose strong constraints on possible packing schemes, assisting in molecular model building when combined with high-resolution methods like solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR).
Insights
Scanning transmission electron microscopy (STEM) measures amyloid fibril mass-per-length, revealing complex assembly pathways and polymorphisms. This technique aids structural modeling for diseases like Alzheimer's.
Area of Science:
- Biophysics
- Structural Biology
- Biochemistry
Background:
- Amyloid fibrils are protein aggregates linked to diseases like Alzheimer's and type II diabetes.
- Similar structures, such as yeast prions, are involved in inherited traits.
- Scanning transmission electron microscopy (STEM) is a key tool for studying amyloid structures.
Purpose of the Study:
- To review the contributions and limitations of STEM in investigating amyloid assembly.
- To explore STEM's role in understanding fibril polymorphisms and structural models.
- To highlight STEM's unique ability to measure mass-per-length (MPL) of individual amyloid filaments.
Main Methods:
- Utilizing scanning transmission electron microscopy (STEM) for mass-per-length (MPL) measurements.
- Analyzing both in vitro assembled and ex vivo amyloid samples.
- Integrating STEM data with high-resolution methods like solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR).
Main Results:
- STEM mass measurements illuminate hierarchical relationships in amyloid fibril assembly.
- Demonstrated that polymorphic fibrils and globular oligomers can co-assemble from a single polypeptide.
- MPL data provides constraints for molecular model building of amyloid structures.
Conclusions:
- STEM is crucial for understanding amyloid assembly pathways and structural diversity.
- The technique enables direct mass measurements, offering unique insights into fibril formation.
- STEM, combined with other methods, advances the molecular modeling of amyloid aggregates.
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