Figure 4: pH dependence of the kinetic parameters for the decarboxylase activity of hDDC toward L-Dopa. (a) Log profile and (b) log profile. The assays were performed at 25°C in 50 mM Bis-Tris-propane at the indicated pH using 50 nM enzyme concentration in the presence of 10 μM exogenous PLP. The points shown are the experimental values, while the curves are from fits to the data using (5) for log and (6) for log .