Development of New Disulfide Bond Formation Methods for Synthesis of Med-size Peptides

Cyclic disulfide peptides are attracting significant attention as a new modality in drug development because their rigid structures enable selective binding to target molecules and confer high resistance to metabolic enzymes. Therefore, new methods for constructing disulfide bonds can contribute to more efficient preparation of these peptides. In this paper, we report the development of disulfide bond-forming methods using 3-nitro-2-pyridinesulfenyl (Npys) compounds and their application to the synthesis of disulfide peptides. The paper covers two topics. First, we developed a one-pot solid-phase disulfide ligation (SPDSL) method, which readily affords disulfide-linked products composed of two thiol-containing components. Based on this SPDSL strategy, we further demonstrate a disulfide-driven synthesis of cyclic peptides from two different peptide fragments. Second, we identified methyl 3-nitro-2-pyridinesulfenate (Npys-OMe) as a mild oxidative reagent that promotes intramolecular disulfide bond formation between two thiols within a peptide. As an application of Npys-OMe, we show that disulfide bond formation can be achieved on thiol-containing peptidyl resins. In addition, a water-soluble Npys derivative functions as a disulfide-forming reagent in aqueous buffer, enabling the direct oxidation of thiol-containing peptides prepared by native chemical ligation.