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Updated: Feb 19, 2026

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
The conformation of the Congo-red ligand bound to amyloid fibrils HET-s(218-289): a solid-state NMR study
Chandrakala Gowda1, Giorgia Zandomeneghi1, Herbert Zimmermann2
1Physical Chemistry, ETH Zurich, 8093, Zurich, Switzerland.
Abstract:
We have previously shown that Congo red (CR) binds site specifically to amyloid fibrils formed by HET-s(218-289) with the long axis of the CR molecule almost parallel to the fibril axis. HADDOCK docking studies indicated that CR adopts a roughly planar conformation with the torsion angle ϕ characterizing the relative orientation of the two phenyl rings being a few degrees. In this study, we experimentally determine the torsion angle ϕ at the center of the CR molecule when bound to HET-s(218-289) amyloid fibrils using solid-state NMR tensor-correlation experiments. The method described here relies on the site-specific 13C labeling of CR and on the analysis of the two-dimensional magic-angle spinning tensor-correlation spectrum of 13C2-CR. We determined the torsion angle ϕ to be 19°.
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