Download MendeleyEffects of N-Terminal Residues on the Assembly of Constrained beta-Hairpin Peptides Derived from A beta.
Samdin, T.D., Wierzbicki, M., Kreutzer, A.G., Howitz, W.J., Valenzuela, M., Smith, A., Sahrai, V., Truex, N.L., Klun, M., Nowick, J.S.(2020) J Am Chem Soc 142: 11593-11601
- PubMed: 32501687
- DOI: https://doi.org/10.1021/jacs.0c05186
- Primary Citation of Related Structures:
6VU4 - PubMed Abstract:
This paper describes the synthesis, solution-phase biophysical studies, and X-ray crystallographic structures of hexamers formed by macrocyclic β-hairpin peptides derived from the central and C-terminal regions of Aβ, which bear "tails" derived from the N-terminus of Aβ. Soluble oligomers of the β-amyloid peptide, Aβ, are thought to be the synaptotoxic species responsible for neurodegeneration in Alzheimer's disease. Over the last 20 years, evidence has accumulated that implicates the N-terminus of Aβ as a region that may initiate the formation of damaging oligomeric species. We previously studied, in our laboratory, macrocyclic β-hairpin peptides derived from Aβ 16-22 and Aβ 30-36 , capable of forming hexamers that can be observed by X-ray crystallography and SDS-PAGE. To better mimic oligomers of full length Aβ, we use an orthogonal protecting group strategy during the synthesis to append residues from Aβ 1-14 to the parent macrocyclic β-hairpin peptide 1 , which comprises Aβ 16-22 and Aβ 30-36 . The N-terminally extended peptides N+1 , N+2 , N+4 , N+6 , N+8 , N+10 , N+12 , and N+14 assemble to form dimers, trimers, and hexamers in solution-phase studies. X-ray crystallography reveals that peptide N+1 assembles to form a hexamer that is composed of dimers and trimers. These observations are consistent with a model in which the assembly of Aβ oligomers is driven by hydrogen bonding and hydrophobic packing of the residues from the central and C-terminal regions, with the N-terminus of Aβ accommodated by the oligomers as an unstructured tail.
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States.
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