Enzyme kinetic parameters for the glucuronidation of estriol, 16-epiestriol, and 17-epiestriol by human liver microsomes (HLM) and human intestine microsomes (HIM)
| HLM | HIM | |||||
|---|---|---|---|---|---|---|
| 3-g | 16-g | 17-g | 3-g | 16-g | 17-g | |
| Estriol | ||||||
| Vmax (pmol/min/mg) | 95 ± 45 | 4347 ± 50 | — | 839 ± 19 | 953 ± 21 | 2095 ± 947 |
| Km (µM) | 313 ± 214 | 13 ± 0.7 | — | 75 ± 4 | 5.1 ± 0.7 | 1119 ± 575 |
| 16-epiestriol | ||||||
| Vmax (pmol/min/mg) | 569 ± 1144 | 8011 ± 106 | ∼8400a | 4111 ± 94 | 1480 ± 35 | 2324 ± 1107 |
| Km (µM) | 2375 ± 5094 | 33 ± 1 | ∼5300a | 50 ± 3 | 43 ± 3 | 1168 ± 629 |
| 17-epiestriol | ||||||
| Vmax (pmol/min/mg) | 805 ± 157 | 128 ± 6 | 5425 ± 67 | 1239 ± 150 | 266 ± 394 | 1633 ± 13 |
| Km (µM) | 380 ± 102 | 7.8 ± 2 | 21 ± 1 | 251 ± 47 | 820 ± 1438 | 1.3 ± 0.14 |
↵a An estimate, as accurate kinetic parameters could not be determined.