Steady-state kinetic parameters were measured at 25 °C. Concentrated protein aliquots were thawed on ice and diluted with a buffer base mix (BBM) containing 50 mM sodium acetate, 100mM tris, and 100 mM bis-tris from pH 4.35-7.5. This buffer system maintains constant ionic strength throughout the pH range examined. A 50 mM solution of the dicyclohexylammonium salt of pNPP was prepared in the buffer base mix. Reactions were run on 96-well plates, diluted enzymes were added to reactions with substrate concentrations from 0.76-22.73 mM and allowed to proceed for 10 minutes. The reactions were quenched using 50 µL of 10 M NaOH, and the amount of the product was assayed from the absorption at 400 nm using the molar extinction coefficient of 18,300 M -1 cm -1 for p-nitrophenolate. Reaction blanks were made using identical conditions replacing the enzyme with buffer, to correct for non-enzymatic hydrolysis of the substrate. The amount of product released and elapsed time were used to calculate the initial rates.