Intein-mediated recombinant expression of monomeric B22Asp desB30 insulin

Insulin controls hyperglycemia caused by diabetes, and virtually all treatments require exogenous insulin. However, the product's extensive post-translational modifications have hindered the manufacture of recombinant insulin.

Here we report a novel production method for a monomeric B22Asp desB30 insulin analog (B22D desB30 insulin). Its precursor, DPIP, is fused to an N-terminal chitin-binding domain and intein self-cleavage tag. The fusion protein is expressed and purified from E. coli and immobilized on chitin resins. DPIP is then released using an optimized pH shift and converted to mature insulin via trypsin digest. The resulting product appears monomeric, > 90% pure and devoid of any exogenous enzyme.

Thus, biologically active insulin analog can be efficiently produced in bacteria and potentially applicable in the treatment of human diabetes.