Abstract:Endo S（EC 3.2.1.96）is a β--N-acetylglucosaminidases from Streptococcus pyogenes, which can specifically hydrolyze the Fc N-glycan of immunoglobulin G（IgG）. In this study, recombinant plasmid BL21(DE3）/pET28a-endo S was constructed and the protein was successfully expressed in E. coli BL21（DE3） cells with confirmed enzymatic activity. Then, single-factor optimization, including screening of basal mediums, nitrogen and carbon sources, mineral salts, expression temperature and time, and initial pH of cultural medium, was performed at shake flask level to express the Endo S in a high level. Under the optimized medium（beef extract 25.4 g/L, yeast powder 10.0 g/L, NaCl 5.0 g/L, glycerol 4.0 g/L, pH 8.0）and condition（induced by 0.25 mM IPTG at 20 ℃ for 24 h）, the yield of recombinant enzyme was 225 mg/L after purification by Ni-resin affinity chromatography, which was 3.5 times higher than that before optimization and 5.6 fold higher than the highest yield reported.
