Inhibitors | Substrates | ||||||
[3H]E2Ga | [3H]E1Sb | [3H]BSPc | |||||
Km | Vmax | Pdif | Km | Vmax | Km | Vmax | |
μM | pmol/min/mg | µl/min/mg | µM | pmol/min/mg | µM | pmol/min/mg | |
No inhibitor | 8.17 ± 2.28 | 250 ± 89 | NA | 0.286 ± 0.054 | 36.4 ± 10.3 | 0.280 ± 0.041 | 20.8 ± 1.0 |
E2G | NA | NA | NA | 0.488 ± 0.072* | 35.7 ± 8.3 | 0.361 ± 0.069 | 18.5 ± 1.9 |
E1S | 18.7 ± 2.2** | 251 ± 22 | NA | NA | NA | 4.78 ± 0.65** | 111 ± 18** |
BSP | 5.80 ± 2.53 | 55.8 ± 24.7** | 0.667 ± 0.642 | 0.677 ± 0.112* | 34.3 ± 11.7 | NA | NA |
NA, not applicable.
↵a Concentration-dependent uptake of [3H]E2G (0.003–100 µM) for 5 min was examined in the absence and presence of unlabeled E1S (0.1 µM) or BSP (0.3 µM).
↵b Concentration-dependent uptake of [3H]E1S (0.003–10 µM) for 1 min was examined in the absence and presence of unlabeled E2G (10 µM) or BSP (0.3 µM).
↵c Concentration-dependent uptake of [3H]BSP (0.007–10 µM) for 5 min was examined in the absence and presence of unlabeled E2G (10 µM) or E1S (10 µM).
↵* P < 0.05; **P < 0.01 compared with parameters determined without any inhibitors.