Preparation and activity evaluation of insulin-like growth factor 1 based on protein structure prediction

Abstract

In order to prepare insulin-like growth factor 1 (IGF-1) more economically and efficiently, the structure prediction and molecular docking of three IGF-1 fusion proteins were performed by computer simulation. The most suitable expression form of IGF-1 fusion protein was screened out. A prokaryotic expression vector of IGF-1 fusion protein was constructed and transformed into Escherichia coli Origami B(DE3) strain to obtain the recombinant strain. After induction with IPTG, the target protein was purified from the soluble fractions of the bacteria cell lysate by affinity chromatography, desalination, thrombin digestion and affinity chromatography of the enzyme digested products. An activity evaluation system was established by 3T3 cell proliferation method and the activity of the obtained IGF-1 was measured. The results showed that the sequence of the IGF-1 fusion protein prokaryotic expression vector was correct and the fusion protein was soluble upon 0.05 mmol/L IPTG induction at 25 ℃ for 16 h. After preliminary purification, thrombin digestion and re-purification, IGF-1 target protein with purity over 90% was obtained. Using the established activity evaluation system, the specific activity of IGF-1 was 2.47×105 U/mg, which was close to the standard product available at the market. The preparation technology of IGF-1 developed in this study may facilitate the development and industrial production of IGF-1 drugs.