Expression, purification, and functional identification of immunoglobulin degrading enzyme IdeS in Escherichia coli / 药学学报

ABSTRACT

In the process of evolution, pathogenic Streptococcus pyogenes secretes an immunoglobulin G-degrading enzyme IdeS which can specifically cleave the hinge region of immunoglobulin G in order to escape the immune response against the host. On the one hand, IdeS can be used for IgG fingerprinting as a tool enzyme combined with mass spectrometry technology. On the other hand, IdeS can be used to treat the antibody-responsive diseases produced by autoimmunity as a therapeutic protein. In this study, the backbone of plasmid pCold was used to construct two expression vectors of recombinant protein IdeS, which were heterologously expressed in Escherichia coli Shuffle T7. After purification by affinity chromatography, the recombinant IdeS activity was detected and their activity differences between the two were compared. Among them, the yield of the recombinant IdeS containing the His6-tag at the N-terminus was 4 mg·L-1, and the cleavage reaction with antibody IgG1 at 1∶200 (m/m) at 37 ℃ for 30 min could complete. However, the yield of the recombinant IdeS containing both the N-terminal His6 tag and the C-terminal silica affinity tag (silica bing peptide, SiBP) is 1.5 mg·L-1, and the degradation reaction with antibody IgG1 at 1∶20 (m/m) at 37 ℃ for 30 min could reach the end. The C-terminal fusion peptide has a great influence on the yield and activity of IdeS, which is not conducive to subsequent application in drug development. Above all, the recombinant IdeS containing the His6-tag at the N-terminus expressed by this system has high activity and can fully meet the needs of antibody drug development and mapping analysis of IgG.