Fig. 1

Expression analysis of the antiEpEX-scFv protein using SDS-PAGE. a The expression level of the target protein was examined in four E. coli strains. The negative control was cells harboring the corresponding plasmid but without induction and the positive control was E. coli K-12 BW25113 cells harboring the corresponding plasmid and were inducted by 0.8 mM IPTG at 37 °C for 24 h (C+)(M: protein marker). b Protein concentration was quantitatively analyzed using BCA. Results showed that the expression levels were lower in E. coli Rosetta^TM T7, E. coli Origami^TM (DE3) and E. coli SHuffle^TM (DE3) compared with E. coli BL21^TM (DE3). Data were analyzed by unpaired, two-tailed Student’s t test and expressed as the mean ± SD of two experiments (*p < 0.05, **p < 0.01)