Regioselective Disulfide Bond Formation during SPS of Human Relaxin-3: Evaluation of An Alternative Method for Removal of the S-Acm Groups via Reaction with Silver Triflate and Subsequent Mild Aqueous DMSO Oxidation

摘要

@@ Relaxin is a peptide hormone member of the insulin superfamily that is composed of two chains which are linked by two inter-disulfide bonds and an intra-disulfide bond within the A-chain. Human relaxin-3, the most recently discovered member of the family is predominantly expressed in the brain[1], and therefore may have an important role in the central nervous system[2]. Recent studies have shown that human relaxin-3 is involved in the regulation of stress and feeding behavior[3]. To further examine this possibility, we previously undertook the chemical synthesis and biological assay of this peptide. In contrast to relaxin-2, the conventional and simple method of random combination of individual S-reduced A-and B-chains in a solution at high pH proved unsuccessful for its preparation[4]. We therefore developed a regioselective disulfide bond formation method to successfully prepare human relaxin-3[5]. However, the recovery of peptide following formation of the third disulfide bind between the A-and B-chains by I2 oxidation has been consistently poor. Here, we examined the use of silver triflate to remove Acm groups on the side chain of Cys in both chains, followed by formation of the third disulfide bond via mild aqueous DMSO oxidation. This method is reported to be side reaction-free[6].