Table 1

Enzyme kinetic parameters of sulfation and glucuronidation for four stereoisomers of troglitazone with KK mouse liver

ConjugationParameterStereoisomer1-a
SSSRRSRR
Sulfation f u 1-b 0.03290.0329 
Component 11-c Component 21-c Total1-d
V max(nmol/min/mg protein)0.0247  ± 0.00510.408  ± 0.0390.0235  ± 0.00190.0447  ± 0.0083
K m (μM)1-e 0.0966  ± 0.02461.53  ± 0.170.356  ± 0.0420.682  ± 0.166
CLu int (ml/min/mg protein)1-f 0.255  ± 0.0840.0308  ± 0.00570.2860.267  ± 0.0390.0661  ± 0.00960.0655  ± 0.0200
V max(nmol/min/g liver)1-g 1.6326.81.552.94
CLu int (ml/min/g liver)1-g 16.82.0318.817.64.354.31
CLu int(ml/min/kg)1-h 67181.1752703174172
Glucuronidation f u 1-i 0.01000.00958
V max (nmol/min/mg protein)1.81  ± 0.381.26  ± 0.232.39  ± 0.570.648  ± 0.069
K m (μM)1-e 0.802  ± 0.1861.32  ± 0.260.600  ± 0.1590.0817  ± 0.0122
CLu int (ml/min/mg protein)1-f 2.25  ± 0.710.948  ± 0.2523.99  ± 1.427.93  ± 1.46
V max (nmol/min/g liver)1-j 96.367.012734.5
CLu int (ml/min/g liver)1-j 12050.4212422
CLu int(ml/min/kg)1-h 4,8002,0208,48016,900
Total CLu int(ml/min/kg)1-k 5,5502,7208,65017,100

  • ↵1-a Data represent the mean ± calculated S.D.

  • ↵1-b Mean of extrapolated f u in the reaction mixture (cytosol) at 2 and 50 μM (see “Methods”).

  • ↵1-c Calculated using v =V max,1 C u/(K m ,1+ C u) +CLu int,2 C u; component 1,V max,1 C u/(K m ,1+ C u); component 2,CLu int,2 C u.

  • ↵1-d Sum of values of component 1 and component 2.

  • ↵1-e K m for C u.C u was calculated by f u × added substrate concentration.

  • ↵1-f CLu int =V max/K m.

  • ↵1-g Obtained by multiplying the value (nmol/min/mg protein) by 65.8.

  • ↵1-h Obtained by multiplying the value (ml/min/g liver) by 40 (Houston, 1994).

  • ↵1-i Mean of unbound fraction in the reaction mixture (microsome activated with Brij 58) at 2 and 50 μM.

  • ↵1-j Obtained by multiplying the value (nmol/min/mg protein) by 53.2.

  • ↵1-k Sum of CLu int of sulfation and glucuronidation for each stereoisomer.