A Perfluoroaryl-Cysteine S_NAr Chemistry Approach to Unprotected Peptide Stapling

Abstract

We report the discovery of a facile transformation between perfluoroaromatic molecules and a cysteine thiolate, which is arylated at room temperature. This new approach enabled us to selectively modify cysteine residues in unprotected peptides, providing access to variants containing rigid perfluoroaromatic staples. This stapling modification performed on a peptide sequence designed to bind the C-terminal domain of an HIV-1 capsid assembly polyprotein (C-CA), showed enhancement in binding, cell permeability, and proteolytic stability properties, as compared to the unstapled analog. Importantly, chemical stability of the formed staples allowed us to use this motif in the native chemical ligation mediated synthesis of a small protein affibody that is capable of binding the Human Epidermal Growth Factor 2 (HER-2) receptor.

Peptide stapling techniques based on different macrocyclisation chemistries

“…39 Peptide stapling was carried out by combining hexafluorobenzene and unprotected peptide in the presence of Tris base and DMF (Fig. 14B).…”

“…(A) Bis-lactam stapled peptide developed by Phelan and co-workers 38. (B) Bis-arylation stapling developed by Pentelute and co-workers 39. …”

Investigating the Proteome Reactivity and Selectivity of Aryl Halides

“…21,22 Lastly, perfluoroaryl groups have been used for covalent peptide stapling. 23 In all these cases, arylation of the cysteine residue is presumed to progress via a nucleophilic aromatic substitution (S N Ar) mechanism, similar to that occurring during the enzymatic conjugation of glutathione to activated aryl groups by glutathione S-transferases. 24 Here, we synthesized a panel of alkyne-functionalized aryl halides and systematically evaluated the reactivity and selectivity of these electrophiles within the context of a complex proteome.…”

Macrocyclic α-Helical Peptide Drug Discovery

“…Furthermore, and related to bis-thioether macrocyclization, a perfluoro-cysteine S N Ar chemistry approach to unprotected peptide stapling has been recently reported. 75 Beyond the above first examples of varying types of macrocylic a-helical peptides, especially stapled peptides, to illustrate the structural diversity of this emerging new class, it is ultimately the 3D-structural and biophysical properties (vide infra) of such molecules that will be key to a greater understanding of their biochemical, cellular, and in vivo pharmacological activities. Exemplifying the 3D-structural diversity of varying subclasses of hydrocarbon-stapled peptides are 6 (double-turn), 7 (single-turn), 14 (stitch), 20 (i,i13 single-turn) and 22 (H-bond surrogate), and their 3D-structures are shown in Figure 9.9.…”