Total Chemical Synthesis of Palmitoyl-Conjugated Insulin

Mengjie Liu; Qingyang Li; Carlie Delaine; Hongkang Wu; Yanni Arsenakis; Barbara F White; Briony E Forbes; Chaitra Chandrashekar; Mohammed Akhter Hossain

doi:10.1021/acsomega.2c07918

Total Chemical Synthesis of Palmitoyl-Conjugated Insulin

ACS Omega. 2023 Apr 6;8(15):13715-13720. doi: 10.1021/acsomega.2c07918. eCollection 2023 Apr 18.

Authors

Mengjie Liu^{1

2}, Qingyang Li^{2

3}, Carlie Delaine⁴, Hongkang Wu², Yanni Arsenakis⁵, Barbara F White⁵, Briony E Forbes⁴, Chaitra Chandrashekar², Mohammed Akhter Hossain^{2

6}

Affiliations

¹ Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, Victoria 3052, Australia.
² The Florey Institute of Neuroscience and Mental Health, Parkville 3052, Australia.
³ Sinochem Pharmaceutical Co., Ltd, 21 Floor Jincheng building, Longpanzhong road, 216, Nanjing 210002, China.
⁴ Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia 5042, Australia.
⁵ Department of Medicine (Austin Health), The University of Melbourne, Heidelberg, Victoria 3084, Australia.
⁶ School of Chemistry, and Department of Biochemistry and Pharmacology, The University of Melbourne, Victoria 3010, Australia.

Abstract

Commercially available insulins are manufactured by recombinant methods for the treatment of diabetes. Long-acting insulin drugs (e.g., detemir and degludec) are obtained by fatty acid conjugation at LysB29 ε-amine of insulin via acid-amide coupling. There are three amine groups in insulin, and they all react with fatty acids in alkaline conditions. Due to the lack of selectivity, such conjugation reactions produce non-desired byproducts. We designed and chemically synthesized a novel thiol-insulin scaffold (CysB²⁹-insulin II), by replacing the Lys^B29 residue in insulin with the Cys^B29 residue. Then, we conjugated a fatty acid moiety (palmitic acid, C16) to CysB²⁹-insulin II by a highly efficient and selective thiol-maleimide conjugation reaction. We obtained the target peptide (palmitoyl-insulin) rapidly within 5 min without significant byproducts. The palmitoyl-insulin is shown to be structurally similar to insulin and biologically active both in vitro and in vivo. Importantly, unlike native insulin, palmitoyl-insulin is slow and long-acting.