Production and purification of recombinant glargine insulin from Escherichia coli BL-21 strain

Diabetes is a chronic metabolic disorder that has affected approximately 463 million populations till date and this number is expected to exponentially rise in the coming decade. Majority of diabetic patients require multiple insulin injections regularly, at the risk of hypoglycemia. As an alternative to conventional insulin, glargine insulin, a long-acting insulin analog that helps in maintaining blood glucose levels, is being preferred. Hence, the present work focuses on glargine insulin production using recombinant E. coli BL-21(DE3) cells through fed-batch fermentation. After fermentation, the cells were lysed through high pressure homogenization to release inclusion bodies containing insulin glargine precursor and the major impurities like Arg (B31)-insulin were reduced by incorporating citraconylation in appropriate concentration. These steps are novel which makes the present study distinct from the other. Furthermore, refolding and enzymatic digestion of insulin glargine precursor was carried out to obtain glargine insulin. Consequently, purification and polishing of glargine insulin were performed by loading onto cation exchange chromatography and reverse-phase high performance liquid chromatography which fetched 98.6% pure product. Through the aforementioned process, from 20 L of culture broth, nearly 0.3 g/L of recombinant glargine insulin with high purity was obtained in two purification steps. Hence, the present study devises an efficient and economical process for large-scale production of glargine insulin.