Figure 2.

Determination of the reduction rate constants (k_red) and dissociation constant (K_d) for reaction of wild-type lactate oxidase with α-¹H-l-mandelate and α-²H-dl-mandelate. Reaction traces such as those of Fig. 1 are strictly single exponential in character, yielding at each concentration a pseudo-first order rate constant, k_obs. The reciprocal of k_obs is here plotted vs. reciprocal of the l-mandelate concentration, to yield values of 1/k_red from the y-intercept and K_d from the slope/intercept (24). The data shown are for α-¹H-l-mandelate (•) and α-²H-dl-mandelate (▴), with the concentration of the latter expressed as the l-form.