Figure 3

2-deoxy-D-galactose (2dG) is a substrate for human galactokinase. Steady state kinetic analysis was carried out as described in Materials and Methods. Each k_cat,app value is derived, using non-linear curve-fitting [25], from a set of rates data at a single sub-saturating substrate concentration. Error bars represent the standard error in k_cat,app as derived by from the fitting process. The lines are non-linear curve fits of the k_cat,app data to the equation k_cat,app = k_cat[substrate]/(K_m + [substrate]). The following parameters were derived from this fitting: k_cat = 4.8 ± 0.3 s^-1; K_m,ATP = 59 ± 9 μM; K_m,2dG = 1100 ± 110 μM; k_cat/K_m,ATP = (8.1 ± 0.8) × 10⁴ l.mol^-1.s^-1; k_cat/K_m,2dG = 4200 ± 270 l.mol^-1.s^-1.