Fig. (4) IgG endopeptidase activity of SeMac. (A) IgG-endopeptidase activity and critical amino acid residues for activity. Human IgG was incubated without (none) or with E. coli lysate containing wild-type SeMac (wt), SeMac^Cys102Ser (C102S), Se- Mac^His272Ala, or SeMac^Asp294Ala at room temperature for 60 min and analyzed by SDS-PAGE. (B) Limited cleavage of horse IgG by SeMac and GAS Mac. Horse total IgG (eIgG), IgG4 (eIgG4), IgG1/IgG4 mixture (eIgG1/4), or human IgG was incubated with purified SeMac or GAS M1 Mac and analyzed by SDS-PAGE.