Figure 2.
Different inhibition kinetics of mature cathepsin K with Gü1303 and Gü2602. Progress curves show the hydrolysis of the fluorogenic substrate Cbz-Gly-Pro-Arg-AMC by mCatK at pH 5.5 in the presence of increasing inhibitor concentrations. (A) Gü1303 exhibited a time-dependent inhibition characterised by non-linear progress curves typical of slow-binding kinetics. (B) Linear progress curves obtained for Gü2602 are characteristic of fast-binding inhibitors. In dose–response plots, the derived steady-state reaction velocities were plotted against inhibitor concentration, and the inhibition constants Ki were obtained after correction by the Cheng-Prusoff and Morrison equations (see Materials and Methods). In the kobs versus [I] plot, the first-order rate constants kobs from the time-dependent progress curves were plotted against inhibitor concentrations to show a linear dependence.