Complete set of PBPs identified with Boc-FL in whole cells of L. monocytogenes. Samples of whole cells (100 μg of total protein) were labeled with Boc-FL at concentrations of 0 (1), 0.5 (2), 1 (3), 2.5 (4), 5 (5), 10 (6), 50 μM (7) and 50 μM plus 100 μg/ml ampicillin (8). Labeled bands were detected directly on the gel, quantified, and their molecular mass estimated. The affinity of each band for Boc-FL (ID50) was estimated from their fluorescence as a function of the concentration of Boc-FL.
The name of the PBP corresponding to each band is indicated on the right, while the positions of molecular weight markers (bars) and unspecific bands (arrowheads) are shown on the left.