Gel electrophoresis of DNS-EGR-CK-labeled extracellular protein from P. gingivalis. Acetone-precipitated extracellular proteins from P. gingivalis W83 and P. gingivalis FLL92 were labeled with the fluorescent irreversible inhibitor DNS-EGR-CK as described in the text and subjected to SDS-PAGE on 4 to 12% gels as described for Fig. 3A. The gels were viewed under UV light to visualize labeled proteins. (A) Lanes: 1, W83 at exponential phase; 2, FLL92 at exponential phase; 3, W83 at stationary phase; 4, FLL92 at stationary phase; 5, FLL92 at exponential phase and treated with urea. (B) Lanes: 1, W83 at exponential phase; 2, FLL92 at exponential phase; 3, W83 at stationary phase; and 4, FLL92 at stationary phase. All the lanes in panel B were labeled with DNS-EGR-CK in the presence of 50 μM leupeptin. Each lane contains 20 μg of protein. The arrow indicates the DNS-EGR-CK-labeled protein band.