FIG. 5.
(A) Inhibition assays of TEM-1 β-lactamase using various BLIP-derived peptides. Peptide binding and inhibition of β-lactamase were determined by measuring the amount of free β-lactamase at various peptide concentrations. β-Lactamase concentrations were 1.0 nM in all assays. For each set of datum points a nonlinear regression fit was calculated as described previously (38). Closed squares, protein kinase C peptide; open squares, cyclic BP46-51 peptide; closed circles, reduced BP46-51 peptide; open circles, BP41-50 peptide. Each datum point is the average for two independent experiments. (B) Inhibition assay of TEM-1 β-lactamase by wild-type BLIP. A Ki of 0.23 nM was determined by using a nonlinear regression fit as described above.