TABLE 2

Kinetic constants for trifluoperazine glucuronidation by alamethicin-treated human liver microsomes and by UGT1A4

For all data, best fit was to the substrate inhibition model. Data are presented as mean ± standard error of parameter fit.




Km

Ksi

Vmax
μM pmol/min · mg protein
HL10 84 ± 1.1 (7.6 ± 0.1)a 65 ± 1.2 (105 ± 2) 820 ± 5.9 (394 ± 2)
HL12 51 ± 1 (6.0 ± 0.2) 122 ± 3.6 (158 ± 6.4) 1180 ± 11 (721 ± 7.1)
HL29 77 ± 1.9 (6.2 ± 0.1) 84 ± 2.4 (164 ± 4.5) 1048 ± 16 (487 ± 3.2)
HL40 35 ± 0.5 (4.7 ± 0.3) 287 ± 6.5 (417 ± 54) 815 ± 5.7 (578 ± 13)
Mean ± S.D. 61 ± 22 (6.1 ± 1.2) 140 ± 101 (211 ± 140) 965 ± 180 (545 ± 139)
UGT1A4
39 ± 3.5 (4.1 ± 0.04)
206 ± 25 (285 ± 3.5)
789 ± 43 (508 ± 1.1)
  • a Data in parentheses are kinetic parameters corrected for nonspecific binding.