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Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
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Aryl-aryl interactions in designed peptide folds: Spectroscopic characteristics and optimal placement for structure
Jordan M Anderson1, Brandon L Kier1, Brice Jurban1
1Department of Chemistry, University of Washington, Seattle, WA, 98195.
Biopolymers
|February 7, 2016
Summary
Aryl/Aryl interactions stabilize polypeptide folds, with edge-to-face orientations identified by NMR and circular dichroism (CD) spectroscopy. Tryptophan and tyrosine residues significantly enhance fold stability and predict CD spectral features.
Area of Science:
- Biophysics
- Structural Biology
- Spectroscopy
Background:
- Aryl/Aryl through-space interactions are crucial for stabilizing small polypeptide folds, including hairpins.
- Previous studies focused on Tryptophan/Tryptophan (Trp/Trp) interactions, necessitating broader investigation into other Aryl/Aryl pairings.
Purpose of the Study:
- To detail the Nuclear Magnetic Resonance (NMR) and Circular Dichroism (CD) spectroscopic features of Aryl/Aryl through-space interactions.
- To establish a scale of fold stability increments for various edge-to-face (EtF) Aryl/Aryl clusters.
- To explore the application of these clusters in designing stable beta-sheet models.
Main Methods:
- Utilized NMR spectroscopy to diagnose T-shape orientations and characterize interactions.
- Employed CD spectroscopy to identify exciton couplets indicative of Aryl/Aryl interactions.
- Investigated Trp-cage folds to identify various Trp/Trp and Trp/Tyrosine cluster geometries.
Main Results:
- NMR data confirmed T-shape orientation for EtF interactions, characterized by ring current shifts.
- CD spectra revealed large exciton couplets in the far-UV region for most EtF interactions.
- A preference for Tryptophan (W) > Tyrosine (Y) ≥ Phenylalanine (F) in face-aryl positions was observed, correlating with fold stability and CD spectral amplitude.
- Specific CD features were identified for W/W, W/Y, Y/W, Y/Y, W/F, and F/Y clusters.
Conclusions:
- EtF Aryl/Aryl interactions are reliable stabilizers of polypeptide folds.
- NMR and CD spectroscopy are powerful tools for characterizing these interactions and predicting fold stability.
- A comprehensive understanding of these interactions aids in the rational design of stable protein structural models.
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