HRMAS 1H NMR Conformational Study of the Resin-Bound Amyloid-Forming Peptide GNNQQNY from the Yeast Prion Sup35

Abstract

The conversion of soluble proteins to insoluble amyloid fibrils is associated with numerous human diseases. The peptide GNNQQNY is a short segment of the yeast prion protein Sup35 that previously has been found to form amyloid fibrils in a similar manner to the protein itself. The approach taken in this work was to attach this peptide sequence to an insoluble polymer matrix through solid phase peptide synthesis and give it the internal freedom to fold into its local conformation in an organic solvent. Observation of its monomeric structure, free from the effects of aggregation, entropic solvent effects, and neighboring molecules, was possible by two-dimensional high-resolution magic angle spinning (1)H NMR spectroscopy. Analysis of the through-bond correlations and through-space interactions observed in the spectra, combined with global energy minimization via computational studies, led to the observation that the peptide chain adopts a compact beta-like turn at the central hydrophilic residues. The technique of peptide attachment to a polymer resin and observation by NMR may allow for future study of single peptide fragments prone to aggregation.