Total turnover numbers of the three UniDesign variants for production of the (R)-5OH metabolite. Hydroxylation of (R)-OMP was carried out at 25 °C in 1× PBS buffer containing 0.5 mM (R)-OMP, 0.5 mM NADP+, 0.25 μM variant enzyme, and 50 μg/ml glucose dehydrogenase. Product (R)-5OH was quantified at 15 min intervals by HPLC until depletion of (R)-OMP. A, representative HPLC traces for the UD1 variant at 0, 0.5, 1, and 2 h intervals. Minor byproducts are marked with asterisks. B, TTNs of the three UniDesign variants. C, yields of the three UniDesign variants for production of the (R)-5OH metabolite. 5OH, 5-hydroxyomeprazole; OMP, omeprazole; TTN, total turnover number.