Table 3. Affinity for TNP-labelled nucleotide binding of trapped Pgp complexes formed from ATP or ADP in the presence of Co2+ ions and determined by enhancement of TNP–nucleotide fluorescence.
Two independent experiments were carried out for determination of each value of Kd, with different preparations of Pgp and the three trapped complexes in each case. The results are expressed as the means±range.
| TNP–ATP | TNP–ADP | |||
|---|---|---|---|---|
| Kd (μM) | ΔFmax | Kd (μM) | ΔFmax | |
| Native Pgp | 50.3±4.7 | 17.8±1.4 | 48.0±4.8 | 18.6±1.0 |
| Pgp+Vi+ATP | 53.8±1.6 | 7.1±0.4 | 31.6±1.5 | 7.3±0.2 |
| Pgp+Vi+ADP | 58.0±3.0 | 8.6±0.5 | 38.0±5.5 | 10.5±0.5 |
| Pgp+BeFx+ATP | 54.2±1.4 | 1.5±0.2 | 42.6±2.1 | 1.8±0.1 |
| Pgp+BeFx+ADP | 59.3±1.4 | 1.7±0.2 | 47.1±5.5 | 2.6±0.1 |
| Pgp+AlFx+ATP | 19.3±2.7 | 4.6±0.2 | 35.7±2.9 | 4.0±0.2 |
| Pgp+AlFx+ADP | 16.9±3.8 | 7.2±0.6 | 31.2±4.1 | 6.5±0.3 |