ABSTRACT
Objective To investigate and optimize the condition of purification and crystallization of oncogenic protein MDM2.Methods MDM2 was expressed in E.coli expression system, and purified by Ni-NTA chelating affinity chromatography and molecular sieve chromatography.The secondary structure of purified protein was analyzed by circular dichroism spectroscopy (CD).Then the crystallization condition of MDM2 was screened and optimized by sitting-drop vapor-diffusion method.Results High purity of MDM2 was obtained by Ni-NTA chelating affinity chromatography and molecular sieve chromatography purification.CD analysis indicated the secondary structure of MDM2 was ordered.Protein-crystallisation experiments illustrated that MDM2 was prone to crystallization under lower pH.Conclusion The optimum pH of MDM2 protein crystallization is 5.5, the optimum protein concentration is 10 mg/mL.