Insight on the Order of Regioselective Ultrafast Formation of Disulfide Bonds in (Antimicrobial) Peptides and Miniproteins

Disulfide-rich peptides and proteins are among the most fascinating bioactive molecules. The difficulties associated with the preparation of these targets have prompted the development of various chemical strategies. Nevertheless, the production of these targets remains very challenging or elusive. Recently, we introduced a strategy for one-pot disulfide bond formation, tackling most of the previous limitations. However, the effect of the order of oxidation remained an underexplored issue. Herein we report on the complete synthetic flexibility of the approach with respect to the order of oxidation of three disulfide bonds in targets that lack the knot motif. In contrast, our study reveals an essential order of disulfide bond formation in the EETI-II knotted miniprotein. This synthetic strategy was applied for the synthesis of novel analogues of the plectasin antimicrobial peptide with enhanced activities against methicillin-resistant Staphylococcus aureus (MRSA), a notorious human pathogen.

Stepwise Construction of Disulfides in Peptides

The disulfide bond plays an important role in biological systems. It defines global conformation, and ultimately the biological activity and stability of the peptide or protein. It is frequently present, singly or multiply, in biologically important peptide hormones and toxins. Numerous disulfide-containing peptides have been approved by the regulatory agencies as marketed drugs. Chemical synthesis is one of the prerequisite tools needed to gain deep insights into the structure-function relationships of these biomolecules. Along with the development of solid-phase peptide synthesis, a number of methods of disulfide construction have been established. This minireview will focus on the regiospecific, stepwise construction of multiple disulfides used in the chemical synthesis of peptides. We intend for this article to serve a reference for peptide chemists conducting complex peptide syntheses and also hope to stimulate the future development of disulfide methodologies.