[Refolding of the fusion protein of recombinant enterokinase light chain rEKL].
The fusion protein of enterokinase light chain, DsbA-rEKL, was expressed mainly in inclusion body in E. coli. The recombinant bacteria was fermented to high density, with high expression of the fusion protein. After being washed with 0.5% Triton X-100 and 4mol/L urea, the inclusion body was dissolved in 6mol/L guanidine and 100mmol/L DTP, derivatized by cystine and refolded by pulse refolding. The strategy of pulse refolding involved the addition of 0.03mg/mL of fusion protein until its final concentration reached 0.3mg/mL. The refolded protein was autocleaved and the active EKL molecule was released after adding 2mmol/L CaCl2. Using the two-step purification processes of IDA-Sepharose chromatography and Q-Sepharose chromatography, the purity of rEKL was found to be above 95%, with a high activity to cleave the recombinant reteplase fusion protein Trx-rPA. The yield of purified rEKL was more than 60mg/L of cultures. As a result, the therapeutic proteins like rPA could be produced on a large-scale in a way such as expressed in the form of fusion proteins.
Yi
Jin-Hua
JH
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China. jhyee2005@126.com
Zhang
Yuan-Xing
YX
D004765:Enteropeptidase / Q000737:chemistry*; D004926:Escherichia coli / Q000235:genetics; D017510:Protein Folding; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000302:isolation & purification
D011993:Recombinant Fusion Proteins; D004765:Enteropeptidase