Cystine-rich heterodimeric peptides or small proteins, such as insulin and relaxin are attractive targets for development of next-generation therapeutics owing to their pleiotropic physiological roles.1 The chemical synthesis of cystine-rich heterodimeric peptides has been an area of interest for many years.2,3 Because of their poor aqueous solubility, aggregation and the number of post-synthetic steps involved in forming disulfide bridges, the chemical synthesis of these peptides is a very tedious and labor-intensive process. The synthetic complexity emphasizes the need for an improved synthetic route to heterodimeric peptides whereby the number of synthetic steps is reduced. Thus, in the search of effective tools for the efficient chemical synthesis of such difficult peptides, we focused on the development of a removable C-peptide (prohormone strategy) between the two peptide chains (A and B) to mimic the in vivo production. In this study, we report development of a removable bis-linker with N-terminal dimedone and C-terminal HMBA-based moieties.4 Due to their stability towards both Boc- and Fmoc-group removal as well as regioselective disulfide bond formation conditions, this bi-functional linker is suitable for the chemical synthesis of these complex peptides in high yield. Details about the design and synthesis of removable bis-linker and a ‘proof of concept’ study for synthesizing two chain peptides will be prescribed.
References:
1) Benítez (2014) Multifaceted Roles of Disulfide Bonds. Peptides as Therapeutics. Rev. 114: 901–926.
2) Belgi et. al (2011) The Chemical Synthesis of Insulin: From the Past to the Present. Immun. Endo. Met. Agents Med. Chem. 11:40-47.
3) Sohma et. al. (2009) Biomimetic Synthesis of Lispro Insulin via Chemically Synthesized Mini-proinsulin Prepared by Oxime Forming Ligation. J. Am. Chem. Soc. 131: 16313-16318.
4) Patil et. al. (2016) A One-Pot Chemically Cleavable Bis-Linker Tether Strategy for the Synthesis of Heterodimeric Peptides. Angew. Chem. Intl. Ed. 55:14552-14556.