FIGURE 7.
pH dependence of the steady-state rate constant kss for the R124L MSDH-catalyzed reaction with PPA as substrate. The pH dependence of kss was studied at 30 °C over the pH range 5.00–8.75 in buffer A. The remaining experimental conditions were as follows: 1 mm NAD, 0.05 m PPA, and 500 μm CoA. Experiments were done twice with experimental errors on the individual points ≤5%. Data (●) were fit by nonlinear least square regression analysis against a single pKapp model that yielded a pKapp of 6.8 ± 0.1 and a kss of 1.3 ± 0.1 s−1 (solid line).