Catalytic parameters were determined from the fit of the Michaelis-Menten equation to the experimental rate vs. substrate concentration profiles. As mentioned above, solubility limits the experimentally available substrate concentration range, making it essentially impossible to experimentally reach saturation. This is, in fact, a common occurrence in studies of Kemp eliminases, and should not prevent the determination of reasonable estimate of the turnover number, kcat, provided that a significant curvature is observed in the experimental Michaelis plots.