Figure 2.

(A) The optimal pH for human leukocyte Glucosylceramidase (GCase) activity is 5.0. The influence of varying pH values on the activity was determined by using sodium acetate buffer in the pH range 4.0–5.5. (B) Lineweaver-Burk plot for Michaelis constant (K_m) determination of GCase at different p-nitrophenyl-β-D-glucopyranoside (PNPG) substrate concentrations (0.71 mM–2.50 mM) and in sodium acetate buffer (50mM, pH 5.0), reveals a K_m of 12.6 mM and V_max of 333 U/mg. All samples were assayed in the presence of 6 mg/ml sodium taurocholate and 70 μl enzyme solution.