FIG. 3.

Processing of purified recombinant His340Ala mutant zymogen by wild-type streptococcal cysteine protease. Active purified streptococcal protease was incubated at 37°C for 30 min with purified mutant zymogen at a molar ratio of 1:10. The samples were analyzed by SDS-PAGE, and the products were visualized by staining with Coomassie brilliant blue. Lanes: 1, molecular mass standards of the sizes indicated at the left; 2, purified wild-type streptococcal cysteine protease; 3, purified Cys192Ser mutant zymogen; 4, purified Cys192Ser mutant zymogen incubated with wild-type streptococcal cysteine protease; 5, purified His340Ala mutant zymogen; 6, purified His340Ala mutant zymogen incubated with wild-type streptococcal cysteine protease.