Evaluation of different culture conditions for high-level soluble expression of human cyclin A2 with pET vector in BL21 (DE3) and spectroscopic characterization of its inclusion body structure

In this paper, we evaluated various parameters of culture condition affecting high-level soluble expression of human cyclin A2 in Escherichia coli BL21(DE3), and demonstrated that the highest protein yield was obtained using TB(no glycerol) + 0.5% glucose medium at 25 °C. By single immobilized metal ion affinity chromatography, we got highly purified human cyclin A2 with a yield ranged from 20 to 30 mg/L. By amyloid-diagnostic dye ThT binding and Fourier transform infrared spectroscopy, we observed a significant decrease in α-helix content and an increase in β-sheet structure in cyclin A2 inclusion body in comparison to its native protein, and confirmed the resemblance of the internal organization of cyclin A2 inclusion body and amyloid fibrils.