Figure 6.

Substrate inhibition of R₁ and R_H2O for wild type HICA(■), HICA-W39F (▲), and HICA-Y181F (●). Data were fit to equation 9. Wild-type HICA data is from (12), where k_max = 34 ± 24 ms⁻¹, K_eff = 75 ± 55 mM, and K_i = 16 ± 2 mM. For HICA-W39F, where k_max = 7.1 ± 1.8 ms⁻¹, K_eff = 22 ± 9 mM, and K_i = 76 ± 14 mM. Reaction conditions were 25 °C, pH 8.75, 10 μM EDTA, 250 mM Na₂SO₄, and 0.06-0.25 μM enzyme.