Proline–Tyrosine Ring Interactions in Black Widow Dragline Silk Revealed by Solid-State Nuclear Magnetic Resonance and Molecular Dynamics Simulations

• Published in: Biomacromolecules Vol. 25; no. 3; pp. 1916 - 1922
• Main Authors: Chalek, Kevin, Soni, Ashana, Lorenz, Christian D., Holland, Gregory P.
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 11.03.2024
• ISSN: 1525-7797; 1526-4602; 1526-4602
• DOI: 10.1021/acs.biomac.3c01351

Selective one-dimensional 13C–13C spin-diffusion solid-state nuclear magnetic resonance (SSNMR) provides evidence for CH/π ring packing interactions between Pro and Tyr residues in 13C-enriched Latrodectus hesperus dragline silk. The secondary structure of Pro-containing motifs in dragline spider silks consistently points to an elastin-like type II β-turn conformation based on 13C chemical shift analysis. 13C–13C spin diffusion measurements as a function of mixing times allow for the measurement of spatial proximity between the Pro and Tyr rings to be ∼0.5–1 nm, supporting strong Pro–Tyr ring interactions that likely occur through a CH/π mechanism. These results are supported by molecular dynamics (MD) simulations and analysis and reveals new insights into the secondary structure and Pro–Tyr ring stacking interactions for one of nature’s toughest biomaterials.