FIG. 4.

Proteolytic activity of Pet protein. (A) Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the 104-kDa secreted Pet protein obtained from the supernatant of the minimal clone HB101(pCEFN1). An L-broth culture was grown overnight at 37°C, and then the supernatant was concentrated and fractionated with a 100-kDa-retention filter. Sizes of marker proteins are indicated in kilodaltons on the right. (B) Proteolytic activity detected by electrophoresing Pet protein alone or mixed with PMSF inhibitor in a precast gelatin zymogram gel. Protease activities are identified as clear bands against a dark blue background after staining with Coomassie blue.