Macrocyclic beta-Sheets Stabilized by Hydrogen Bond Surrogates.
Nazzaro, A., Lu, B., Sawyer, N., Watkins, A.M., Arora, P.S.(2023) Angew Chem Int Ed Engl 62: e202303943-e202303943
- PubMed: 37170337 
- DOI: https://doi.org/10.1002/anie.202303943
- Primary Citation of Related Structures:  
8DPY - PubMed Abstract: 
Mimics of protein secondary and tertiary structure offer rationally-designed inhibitors of biomolecular interactions. β-Sheet mimics have a storied history in bioorganic chemistry and are typically designed with synthetic or natural turn segments. We hypothesized that replacement of terminal inter-β-strand hydrogen bonds with hydrogen bond surrogates (HBS) may lead to conformationally-defined macrocyclic β-sheets without the requirement for natural or synthetic β-turns, thereby providing a minimal mimic of a protein β-sheet. To access turn-less antiparallel β-sheet mimics, we developed a facile solid phase synthesis protocol. We surveyed a dataset of protein β-sheets for naturally observed interstrand side chain interactions. This bioinformatics survey highlighted an over-abundance of aromatic-aromatic, cation-π and ionic interactions in β-sheets. In correspondence with natural β-sheets, we find that minimal HBS mimics show robust β-sheet formation when specific amino acid residue pairings are incorporated. In isolated β-sheets, aromatic interactions endow superior conformational stability over ionic or cation-π interactions. Circular dichroism and NMR spectroscopies, along with high-resolution X-ray crystallography, support our design principles.
Organizational Affiliation: 
Department of Chemistry, New York University, 100 Washington Square East, NY 10013, New York, USA.