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Updated: Apr 3, 2026
Characterization of pH-Dependent Reversible Self-Assembly of Amyloid Beta 1-40-Coated Gold Colloids
Published on: March 21, 2025
Synthesis and characterization of the amyloid β40 dimer model with a linker at position 30 adjacent to the
Kazuma Murakami1, Takashi Suzuki1, Mizuho Hanaki1
1Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
Abstract:
Amyloid fibrils in senile plaque mainly consist of the 40-mer and 42-mer amyloid β-proteins (Aβ40 and Aβ42). Although Aβ42 plays more important role in the pathogenesis of Alzheimer's disease (AD), Aβ40 could be involved in the progression of AD pathology because of its large amount. Recent studies revealed that variable sizes of Aβ oligomers contributed to the neuronal death and cognitive dysfunction. However, how large oligomeric species are responsible for AD pathogenesis remains unclear. We previously proposed a toxic dimer model of Aβ with turn structure at positions 22 and 23 using solid-state NMR and systematic proline replacement. Based on this model, we herein show the synthesis and biological activities of an E22P-Aβ40 dimer at position 30, which was connected to l,l-2,6-diaminopimeric acid. The E22P-Aβ40 dimer formed stable 6∼8-mer oligomers without amyloid fibrils, but was not neurotoxic on human neuroblastoma cells. On the other hand, E22P-Aβ40 generated high molecular-weight oligomers into fibrils, and showed the neurotoxicity. These results suggest that such kind of Aβ40 dimer with a parallel β-sheet might not be pathological.
Insights
Amyloid beta-40 (Aβ40) dimers with specific structures may not cause Alzheimer's disease (AD) pathology. Modified Aβ40 dimers forming stable oligomers, rather than fibrils, showed no neurotoxicity in this study.
Area of Science:
- Neuroscience
- Biochemistry
- Molecular Biology
Background:
- Amyloid fibrils, primarily Aβ40 and Aβ42, accumulate in Alzheimer's disease (AD) senile plaques.
- While Aβ42 is key in AD pathogenesis, Aβ40's abundance suggests a role in disease progression.
- Oligomeric amyloid-beta species are implicated in neuronal death and cognitive decline, but their specific roles remain unclear.
Purpose of the Study:
- To investigate the pathological potential of a modified amyloid beta-40 (Aβ40) dimer.
- To explore the relationship between Aβ40 oligomerization, structure, and neurotoxicity.
Main Methods:
- Synthesis of an E22P-Aβ40 dimer linked to l,l-2,6-diaminopimeric acid.
- Analysis of oligomer formation and structure using biophysical techniques.
- Assessment of neurotoxicity on human neuroblastoma cells.
Main Results:
- The synthesized E22P-Aβ40 dimer formed stable 6-8-mer oligomers without amyloid fibrils, exhibiting no neurotoxicity.
- Under different conditions, E22P-Aβ40 generated high molecular weight oligomers that formed fibrils and demonstrated neurotoxicity.
- These findings suggest that specific Aβ40 dimer structures with parallel β-sheets may not be inherently pathological.
Conclusions:
- The structural characteristics of Aβ40 oligomers significantly influence their pathological potential.
- Not all Aβ40 oligomeric species contribute to Alzheimer's disease pathogenesis.
- Further research into Aβ structure-toxicity relationships is crucial for understanding AD.
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