Recombinant Exendin-4 Analogue Ew Cloning, Expression, Purification And Biological Activity Studies

Exendin-4 is a 39-amino acid peptide isolated from the salivary secretion of the Gila monster (Heloderma suspectum). Exendin-4 is a potent and long-acting agonist of glucagon-like peptide (GLP)-1 receptor. But the chemical synthesis of Exendin-4 is costly and Exendin-4 itself is of high immunogenicity. In the present study, a 32-amino acid analogue of Exendin-4, EW, was designed and the EW gene was obtained by PCR with a trypsin site at N-terminus and a termination codon at C-terminus. EW was highly expressed in tandem in Escherichia coli strain JM109. The inclusion bodies were purified and recombinant EW was obtained by trypsin cleavage of the fusion protein followed by purification. The yielding recombinant EW was 200-250 mg/litre broth. The obtained recombinant EW showed a glucose-lowering effect in vivo which was identical to Exendin-4 in potency and duration. The analogue EW is a promising anti-diabetic agent and can be commercially produced by genetic engineering.