FIG. 2.

PBPs of E. coli DC0 labeled with ³H-benzylpenicillin, in competition with AM-112. Concentrations of AM-112 (μg/ml) are shown along the top of the gel. The PBP pattern of E. coli DC0 was determined by labeling with ³H-benzylpenicillin (10 to 30 Ci/mmol) after preincubation for 45 min at 37°C with AM-112 at the concentrations shown. Separation of the labeled proteins was achieved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis using 7.5% (wt/vol) acrylamide gels following the method of Laemmli (12). After electrophoresis, the gel was soaked in Amplify (Amersham) for 30 min. The gel was dried on a gel drier (Bio-Rad, Hemel Hempstead, United Kingdom) for 2 h. Hyperfilm MP (Amersham) was placed in contact with the dried gel and was exposed to the gel for 2 weeks at −70°C prior to visualization.