Activity of GSH conjugation of Tri was measured by incubating human liver or kidney subcellular fractions (1 mg protein/ml) at 37°C with 5 mM GSH and 7.8 μM to 1 mM Tri for 20 min (liver cytosol and microsomes, kidney microsomes) or 10 min (kidney cytosol). DCVG formation was measured by HPLC after derivatization of acid extracts of samples. Kinetic parameters were calculated from Eadie-Hofstee plots from the data presented in Figs. 7 and 8, which were obtained from measurements from three separate sets of determinations.