FIG 4.
Kinetics of PenI and the C69F variant. (A) Hydrolysis of 25 μM ceftazidime by 10 μM PenI. (B) Biphasic hydrolysis of 25 μM ceftazidime by 10 μM the C69F variant measured on a stopped-flow apparatus. (C) Hydrolysis of 50 μM nitrocefin by 350 nM PenI inhibited by increasing concentrations of ceftazidime. (D) Hydrolysis of 50 μM nitrocefin by 10 μM the C69F variant inhibited by increasing concentrations of ceftazidime. (E) The kobs values obtained by fitting the progress curves in panel C to the equation in Materials and Methods plotted versus the ceftazidime concentration. (F) The kobs values obtained by fitting the progress curves in panel D to the equation in Materials and Methods plotted versus the ceftazidime concentration. a.u., arbitrary units.