Apparent kinetic parameters for the N-glucuronidation of (R)-ketotifen in human liver microsomes with and without addition of Triton X-100
| Kinetic Type | HL 18 | HL 22 | HL 23 | Mean ± S.D. | ||||
|---|---|---|---|---|---|---|---|---|
| Parameter | + Det.∗ | − | + Det. | − | + Det. | − | + Det. | − |
| One Enzyme | ||||||||
| K M | 14 | 6.1 | 17 | 6.5 | 13 | 7.1 | 15 ± 2 | 6.6 ± 0.5 |
| V max | 500 | 150 | 540 | 280 | 360 | 140 | 470 ± 90 | 190 ± 75 |
| V max/K M | 35 | 25 | 32 | 42 | 28 | 20 | 32 ± 4 | 29 ± 12 |
| r 2 | 0.998 | 0.991 | 0.994 | 0.993 | 0.999 | 0.995 | ||
| Two Enzymes | ||||||||
| K M1 | 3.5 | 2.6 | 3.7 | 1.1 | 2.4 ± 1.2 | |||
| V max1 | 110 | 120 | 40 | 26 | 85 ± 52 | |||
| V max1/K M1 | 31 | 47 | 11 | 24 | 34 ± 12 | |||
| K M2 | 40 | 16 | 16 | 11 | 22 ± 16 | |||
| V max2 | 56 | 165 | 330 | 120 | 113 ± 54 | |||
| V max2/K M2 | 1.4 | 10 | 21 | 11 | 7.5 ± 5 | |||
| r 2 | 0.995 | 0.996 | 0.999 | 0.998 | ||||
KM values are given in μM, Vmaxin pmol/min/mg protein, Vmax/KMin μl/min/mg protein.
Parameters were calculated according to one- and two-enzyme Michaelis-Menten kinetics.
∗, Det. = Triton X-100 0.02% as detergent.