A novel method for the chaperone aided and efficient production of human proinsulin in the prokaryotic system

With the rapid spread of diabetes in human society, the demand for insulin and its precursor (proinsulin) continues to rise. Therefore, the introduction of new methods for their production is essential. In the present study, human proinsulin, while ligated to αB-crystallin chaperone, was effectively expressed in the prokaryotic host system and then purified by the ion-exchange chromatography at high purity (>97%). In the next step, human proinsulin with relatively high efficiency was released chemically from the hybrid protein (αB-pIns) and then purified using an appropriate gel filtration column. The SDS-PAGE and HPLC analyses confirmed the high purity, while mass spectroscopy assessment verified the exact molecular mass of the human proinsulin. Using a well-established protocol, the protein was folded in a one-step folding process with a yield of about 70%. The assessment of the secondary structures of the human proinsulin by Raman and FTIR spectroscopy suggested that this protein is rich in α-helix. Also, the conformation of disulfide bonds in the folded proinsulin was confirmed by Raman spectroscopy. The recombinant human proinsulin also demonstrated hypoglycemic activity and mitogenic action (induction of cell proliferation). The method proposed in this work for the production of human proinsulin is easy to run and does not depend on expensive and complex equipment. Thus, it can be used in the industrial production of human proinsulin.