Probing Intermolecular Interactions within the Amyloid ? Trimer Using a Tethered Polymer Nanoarray.

ABSTRACT: Amyloid oligomers are considered the most neurotoxic species of amyloid aggregates. Spontaneous assembly of amyloids into aggregates is recognized as a major molecular mechanism behind Alzheimer's disease and other neurodegenerative disorders involving protein aggregation. Characterization of such oligomers is extremely challenging but complicated by their transient nature. Previously, we introduced a flexible nanoarray (FNA) method enabling us to probe dimers assembled by the amyloid ? (14-23) [A? (14-23)] peptide. The study presented herein modifies and enhances this approach to assemble and probe trimers of A? (14-23). A metal-free click chemistry approach was used, in which dibenzocyclooctyne (DBCO) groups were incorporated at selected sites within the FNA template to click A? (14-23) monomers at their terminal azide groups. Atomic force microscopy (AFM) force spectroscopy was employed to characterize the assemblies. The force measurement data demonstrate that the dissociation of the trimer undergoes a stepwise pattern, in which the first monomer dissociates at the rupture force ?48 ± 2.4 pN. The remaining dimer ruptures at the second step at a slightly larger rupture force (?53 ± 3.2 pN). The assembled trimer was found to be quite dynamic, and transient species of this inherently dynamic process were identified.

SUBMITTER: Maity S 

PROVIDER: S-EPMC6093788 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature