Figure 3.

Concentration dependence of the ICT concentration on the observed rate of NADPH production in the normal reaction (37 °C). The determined k_obs values were obtained from two different enzyme preparations to ensure reproducibility. The k_obs values resulting from each of the two enzyme preparations are distinguished by using either a circle or an × in the plots. The observed rate constants (k_obs) were calculated from the linear range of the slopes of plots of concentration versus time using GraphPad Prism software (GraphPad, San Diego, CA). These k_obs values were then fit to a hyperbolic equation to generate k_cat and K_m values, and the standard error listed in Table 1 results from the deviance from these hyperbolic fits is indicated. The determined k_obs values were obtained from two different enzyme preparations to ensure reproducibility. Results from assays at 21 °C are shown in supplemental Fig. S3. A, WT IDH1. B, H133Q IDH1. C, A134D IDH1. D, R100Q IDH1. E, R132H IDH1. F, R132C IDH1. G, R132G IDH1.