Mono‐Substituted Hydrocarbon Diastereomer Combinations Reveal Stapled Peptides with High Structural Fidelity

• Published in: Chemistry : a European journal 2018-02, Vol.24 (9), p.2094-2097
• Main Authors: McWhinnie, Fergus S., Sepp, Kristel, Wilson, Charlotte, Kunath, Tilo, Hupp, Ted R., Baker, Terry S., Houston, Douglas R., Hulme, Alison N.
• Format: Article
• Language: English
• Subjects: Chemistry; Circular dichroism; Dichroism; Fidelity; Helicity; NMR; NMR spectroscopy; Nuclear magnetic resonance; Peptides; Protein structure; Proteins; ring-closing metathesis; stapled peptides; Structural analysis; structure elucidation
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201705983

Modified peptides, such as stapled peptides, which replicate the structure of α‐helical protein segments, represent a potential therapeutic advance. However, the 3D solution structure of these stapled peptides is rarely explored beyond the acquisition of circular dichroism (CD) data to quantify bulk peptide helicity; the detailed backbone structure, which underlies this, is typically undefined. Diastereomeric stapled peptides based on helical sections of three proteins (αSyn, Cks1 and CK1α) were generated; their overall helicity was quantified by CD; and the most helical peptide from each series was selected for structural analysis. Solution‐phase models for the optimised peptides were generated using NMR‐derived restraints and a modified CHARMM22 force field. Comparing these models with PDB structures allowed deviation between the stapled peptides and critical helical regions to be evaluated. These studies demonstrate that CD alone is not sufficient to assess the structural fidelity of a stapled peptide. Mix and match! Rapid and accessible protocol facilitates the identification of stapled peptides with backbone structures which replicate that of the parent protein with high fidelity. These techniques could be applied to any helical protein target enabling pre‐validation of synthesized material before in vitro or in vivo analysis.