FIGURE 7.
A, kinetic parameters of the ECE-2 enzymatic activity using PL405. Increasing concentrations of PL405 were incubated 60 min at 37 °C in 200 mm sodium acetate, pH 5.5, containing 250 ng/ml of ECE-2. The mean values of two independent experiments performed in duplicate are represented. The Km of the substrate is 21 ± 4 μm, the catalytic constant (kcat) is 0.17 ± 0.02 s−1, and the kcat/Km is 8.1 × 103 ± 0.9 × 103 m−1·s−1. B, cleavage of the PL405 (20 μm) by ECE-2 as a function of enzyme concentrations in vitro (incubation 3 h at 37 °C).