RESUMO
Objective To study the coexpression of protein folding modulators,including chaperones(DnaK,DnaJ,and GroEL-GroES) and disulfide isomerase Dsb molecules(DsbA and DsbC) on the bioactivity of eukaryotic expressed urokinase(UK).Methods The gene sequences of DnaK,DnaJ,GroEL-GroES,DsbA and DsbC were isolated from the chromosome of E.coli by PCR.The obtained fragments mentioned above were cloned into the plasmid pBAD-1 under the control of araB promoter and then the plasmids were transformed into E.coli BW25113 and HB101 together with a compatible vector pQE-UK.The amount of expressed UK was measured by Bradford method and its activity was analyzed by fibrin plate method for its fibrinolysis.Results The activity of expressed UK was increased by co-expressing with DnaK,GroEL-GroES,DsbA,and DsbC in BW25113.Among them,the highest activity was achieved by co-expressing with GroEL-GroES.Conclusion Co-expressing of chaperones or disulfide isomerase can improve the bioactivity of UK expressed in E.coli.