Observed rate constant (kobs) values for IDH1 R132H inhibition at different Ivosidenib concentrations and with varied concentrations of MgCl2. The slope=kon, the intercept=koff, and intercept/slope=Kd(see Eq. 2). Conditions: (FNR+IDH1R132H)@ITO/PGE electrode, electrode area 0.06 cm2, electrode rotation rate 1000 rpm, temperature 25 °C,E=−0.5 V vs SHE, O2<1 ppm, volume 4 mL, pH=8 (20 mM each of: MES, TAPS, CHES), 10 μM NADPH, enzyme loading ratios (molar): FNR/IDH1R132H; 1/2.5. The data in panel C were measured at MgCl2=10 mM; the data in panel D were measured at 2OG=1 mM. Note: data in black in panels C and D are the same.
