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.
Kevin Chalek, Ashana Soni, Christian D. Lorenz, and Gregory P. Holland
Biomacromolecules Article ASAP DOI: 10.1021/acs.biomac.3c01351