FIG. 2.
Zymogram analysis of protease activity in exoproteins of S. aureus. Lane 1, S. aureus 8325-4; lane 2, PC6911 (agr); lane 3, PC1839 (sarA); lane 4, PC18391 (sarA agr). Exoproteins are from the equivalents of 0.05 (lanes 1 and 2) and 0.005 (lanes 3 and 4) OD600 units of original culture. Stationary-phase samples (T = 18 h) were prepared and separated on a 12% (wt/vol) polyacrylamide gel with casein as the substrate, and the gel was renatured as described in Materials and Methods. Proteolytic activity can be seen as a zone of clearing on the gel, indicated by arrows. The molecular masses of protein standards (in kilodaltons) are shown.