Assays were performed in pH 7.5 Tris buffer at 37°C for 0.25–1.0 hr, using whole-cell homogenates of HK293 cells expressing UGT1A3. The concentration of UDP-glucuronic acid was 2.0 mM, and the aglycone concentrations were 0.5 mM, unless otherwise noted. Enzymatic rates are expressed as the mean ± SD of determinations from three transfections or the average determinations using cell homogenates from two transfections.

↵4-a ND, glucuronide formation was not detected (limits of detection, 2.0 pmol/min/mg of protein).