AZT, entacapone, and 4-MU glucuronidation kinetic type and parameters
The values represent a best-fit result ± S.E. The reaction velocity is given in actual rates for all of the enzymes. See Materials and Methods for additional details.
| Substrate | Enzyme Source | Enzyme Kinetic Parameters | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| No BSA (Control) | 0.1% BSA | 1% BSA | ||||||||
| Km | Vmax | Kinetic Model (r2)/Ki (μM) or β | Km | Vmax | Kinetic Model (r2)/Ki (μM) or β | Km | Vmax | Kinetic Model (r2)/Ki (μM) or β | ||
| μM | nmol · min−1 · mg−1g | μM | nmol · min−1 · mg−1 | μM | nmol · min−1 · mg−1 | |||||
| Zidovudine | HLM | 586.1 ± 23.6 | 0.41 ± 0.01 | MM (0.99) | 76.71 ± 1.53 | 0.46 ± 0.01 | MM (0.99) | |||
| UGT2B7 | 381.2 ± 13.9 | 0.36 ± 0.01 | MM (0.99) | 134.5 ± 7.74 | 0.45 ± 0.01 | MM (0.99) | ||||
| Entacapone | HLM | 25.56 ± 3.90 | 7.13 ± 0.38 | SI (0.90) Ki = 1919 ± 547 | 1.26 ± 0.16 | 12.49 ± 0.29 | SI (0.87) Ki = 1898 ± 404 | |||
| Ks = 66.27 ± 11.25 | 15.73 ± 1.38 | TSI (0.88) β = 0.303 ± 0.050 | Ks = 6.11 ± 0.34 | 36.6 ± 0.96 | TSI (0.97) β = 0.27 ± 0.01 | |||||
| UGT1A9 | 18.63 ± 2.05 | 8.35 ± 0.31 | SI (0.94) Ki = 1789 ± 334 | 2.37 ± 0.26 | 16.95 ± 0.43 | SI (0.94) Ki = 2116 ± 456 | ||||
| Ks = 50.03 ± 6.84 | 18.78 ± 1.29 | TSI (0.90) β = 0.30 ± 0.03 | Ks = 8.85 ± 0.51 | 44.97 ± 1.30 | TSI (0.98) β = 0.30 ± 0.01 | |||||
| UGT1A9 (UDPGA kinetics) | 257.7 ± 27.8 | 5.83 ± 0.16 | MM (0.96) | 247.4 ± 12.9 | 15.06 ± 0.20 | MM (0.99) | ||||
| UGT1A9 Supersomes | 13.74 ± 1.95 | 12.44 ± 0.60 | SI (0.94) Ki = 1494 ± 454 | 5.41 ± 0.40 | 33.41 ± 0.66 | SI (0.99) Ki = 1301 ± 191 | ||||
| Ks = 39.12 ± 4.97 | 29.24 ± 2.02 | TSI (0.95) β = 0.29 ± 0.04 | Ks = 16.49 ± 1.31 | 80.12 ± 3.14 | TSI (0.99) β = 0.32 ± 0.02 | |||||
| 4-MU | UGT1A9 | 11.77 ± 1.25 | 1.92 ± 0.06 | SI (0.93) Ki = 984 ± 111 | 2.63 ± 0.43 | 3.69 ± 0.11 | SI (0.96) Ki = 328 ± 30 | 2.87 ± 0.25 | 4.77 ± 0.13 | SI (0.98) Ki = 113 ± 9 |
| Ks = 43.67 ± 3.51 | 5.12 ± 0.17 | TSI (0.91) β = 0.19 ± 0.02 | Ks = 18.31 ± 1.41 | 9.10 ± 0.35 | TSI (0.88) β = 0.15 ± 0.02 | Ks = 10.95 ± 0.65 | 13.45 ± 0.30 | TSI (0.96) β = 0.09 ± 0.01 | ||
| UGT1A9 (UDPGA kinetics) | 180.1 ± 21.6 | 1.34 ± 0.04 | MM (0.94) | 105.8 ± 8.7 | 2.66 ± 0.04 | MM (0.96) | ||||
| UGT1A9 Supersomes | 9.03 ± 0.96 | 6.19 ± 0.21 | SI (0.94) Ki = 780 ± 118 | 2.94 ± 0.32 | 12.25 ± 0.35 | SI (0.94) Ki = 348 ± 35 | 1.93 ± 0.08 | 13.60 ± 0.18 | SI (0.99) Ki = 256 ± 18 | |
| Ks = 32.06 ± 3.76 | 16.26 ± 0.95 | TSI (0.88) β = 0.22 ± 0.03 | Ks = 15.31 ± 1.40 | 37.71 ± 1.53 | TSI (0.85) β = 0.15 ± 0.02 | Ks = 6.81 ± 0.40 | 35.86 ± 1.05 | TSI (0.98) β = 0.24 ± 0.01 | ||
MM, Michaelis-Menten; SI, substrate inhibition; TSI, two sites substrate inhibition.