Kinetic parameters for DHT diglucuronidation in human liver microsomes (HLM), human intestinal microsomes (HIM), and recombinant human UGT1A8
DHT monoglucuronide (50-2000 μM) was incubated with 1 mg/ml microsomes in the presence of UDPGA at 37°C for 240 min. Kinetic parameters were calculated by fitting triplicate data to the appropriate kinetic model. Each value represents the estimate ± the standard error of the estimate. Numbers in parentheses are kinetic values for reference.
Enzyme | Km | Vmax | Vmax/Km | Ksi a |
|---|---|---|---|---|
| μM | pmol/min/mg protein | μl/min/mg protein | μM | |
| HLMb | 527.9 ± 66.5 | 0.256 ± 0.012 | 0.486 × 10-3 | |
| HIMb | 653.4 ± 69.0 | 1.303 ± 0.056 | 1.994 × 10-3 | |
| UGT1A8c | 382.3 ± 79.7 | (0.107 ± 0.015) | (0.279 × 10-3) | (964.4 ± 231.7) |