Table 1.
Kinetic parameters and inhibitor profile of T. vaginalis nucleoside transporters (Average and SEM, µM).
| Adenosine (HA) |
Guanosine (HA) |
Inosine (LA) |
Uridine (HA) |
Cytidine (HA) |
Thymidine (HA) |
Adenosine (LA) |
Cytidine (LA) |
Thymidine (LA) |
|
|---|---|---|---|---|---|---|---|---|---|
| Km,app | 6.2 ± 0.6 | 9.0 ± 0.6 | 196 ± 18 | 5.5 ± 1.8 | 7.2 ± 1.8 | 13.2 ± 0.8 | 59 ± 6 | 348 ± 18 | 470 ± 104 |
| Vmax 1 | 9.5 ± 2.4 | 0.91 ± 0.25 | 2.6 ± 0.4 | 1.5 ± 0.5 | 0.83 ± 0.06 | 6.7 ± 1.8 | 31 ± 2 | 6.7 ± 1.8 | 9.4 ± 2.5 |
| Vmax/Km | 1.5 | 0.10 | 0.013 | 0.27 | 0.12 | 0.05 | 0.52 | 0.019 | 0.020 |
| Ki,app | |||||||||
| Adenosine | 4.1 ± 0.9 | 6.4 ± 1.7 | 8.2 ± 0.6 | 2.2 ± 0.3 | 39 ± 8 | 357 ± 32 | 73 ± 6.9 | ||
| Inosine (HA) | 5.2 ± 1.2 | 14.1 ± 5.7 | 3.8 ± 0.9 | ND | 78 ± 15 3 | ND | ND | ND | |
| Inosine (LA) | 348 ± 127 | ND | 231 ± 23 | ND | N/A | ND | ND | ND | |
| Guanosine | 12.2 ± 2.4 | 7.4 ± 2.9 | ND | 16.7 ±2.6 | 36 ± 7 | >250 | ND | ND | |
| Uridine | 3.7 ± 1.0 | 7.9 ± 1.3 | 3.6 ± 1.1 | 2.0 ± 0.5 | 12 ± 1 | 376 ± 63 | ND | ND | |
| Thymidine | 274 ± 45 | 206 ± 62 | ND | ND | ND | 557 ± 135 | ND | ||
| Cytidine | 17.9 ± 4.4 | 19 ± 0.9 | ND | 15.6 ± 2.3 | ~15 2 | 116 ± 5 | ~250 2 | ||
| Adenine | ~1000 | ND | ND | ND | ND | >1000 | >1000 | ND | ND |
| Hypoxanthine | >500 | ND | ND | ND | ND | >1000 | >1000 | ND | ND |
| Uracil | ND | ND | ND | ND | ND | >1000 | >10000 | ND | ND |
HA, high affinity; LA, low affinity; ND, not determined; N/A, not applicable.
1.
Units for Vmax are pmol(107 cells)−1s−1.
2.
Estimated rough average from three separate experiments yielding biphasic plots.
3.
Based on monophasic plots. This transport activity has only one Ki,app for inosine.