Figure 3.

The kinetic constant k_cat/K_m (M⁻¹⋅s⁻¹) for the hydrolysis of 4-nitrophenylacetate catalyzed by human CA XII. Measurements were made at 25°C using solutions maintained at an ionic strength of 0.2 M using Na₂SO₄ and containing 5 μM EDTA and 25 mM of one of the buffers listed in the text. The solid line is a least-squares fit with the maximal of k_cat/K_m at 90 ± 2 and pK_a 7.1 ± 0.1.