Figure 5.

Kinase activity assays utilizing the CDK2/cyclin E kinase complex to characterize covalent binding interactions with 2. (A) Enzyme inhibition by 2 exhibited time-dependence of the IC₅₀, here plotted in relative units (RU). (B) CDK2/cyclin E activity as a function of preincubation time was fit to determine the k_obs rate constants which are plotted as a function of 2 concentration. Mean k_obs reported ± SEM. These data were fit to determine K_I (the apparent inhibitor affinity), k_inact (the maximal inactivation rate), and the ratio k_inact/K_I (potency).