Fig. (9) Saturation of IleRS by IBMK.The incubation mixtures were the same as in Figure 8. The fraction of IBMK-inactivated IleRS, as deduced from kinetics data from Figure 8, is represented as a function of free IBMK concentration. From this saturation curve, the half-effect concentration of IBMK in the inactivation of IleRS was estimated to be 0.1 mM.