Stabilization of peptides against proteolysis through disulfide-bridged conjugation with synthetic aromatics.

Peptides have been promising molecular scaffolds for the development of potential therapeutics with high affinity and specificity to biomacromolecules. However, their inherent proteolytic instability significantly hampers their biological applications. Strategies that can stabilize peptides against proteolytic digestion on the basis of noncovalent interactions-without extensive manipulation of the sequence or use of unnatural residues-are greatly desired. In this work, we developed a general, convenient, and efficient strategy for the stabilization of peptides against proteolysis, which involves noncovalent π-π interactions between aromatic amino acid residues in peptides and synthetic electron-deficient aromatics (NDI), together with the implication of steric hindrance (from the bulky NDI moiety), and the enhancement of peptide α-helicity. This strategy is complementary in concept to the conventional well-established covalent approaches for peptide stabilization, and is thus promising for being utilized, in combination with the latter ones, to circumvent the problem of proteolytic instability of peptides. We envisioned that this study should provide invaluable guidelines to the design and synthesis of organic molecule-peptide hybrids with significantly improved proteolytic resistance, and benefit the development of peptide therapeutics and probes.