A Study of the α-Helical Intermediate Preceding the Aggregation of the Amino-Terminal Fragment of the β Amyloid Peptide (Aβ1–28)
- 22 September 2011
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry B
- Vol. 115 (44), 12978-12983
- https://doi.org/10.1021/jp2050993
Abstract
The β amyloid (Aβ) peptide aggregates to form β-rich structures that are known to trigger Alzheimer’s disease. Experiments suggest that an α-helical intermediate precedes the formation of these aggregates. However, a description at the molecular level of the α-to-β transition has not been obtained. Because it has been proposed that the transition might be initiated in the amino-terminal region of Aβ, we studied the aggregation of the 28-residue amino-terminal fragment of Aβ (Aβ1–28) using molecular dynamics and a coarse-grained force field. Simulations starting from extended and helical conformations showed that oligomerization is initiated by the formation of intermolecular β-sheets between the residues in the N-terminal regions. In simulations starting from the α-helical conformation, forcing residues 17–21 to remain in the initial (helical) conformation prevents aggregation but allows for the formation of dimers, indicating that oligomerization, initiated along the nonhelical N-terminal regions, cannot progress without the α-to-β transition propagating along the chains.Keywords
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