TABLE 1. Assays of function in E. coli strain pSWM132/DK8 expressing ATP synthase in which α subunit contains a C-terminal 6-His tag.
| Strain | Growth on Succinate | Membrane ATPase activitya | Proton pumping activityb |
|---|---|---|---|
| Wild-typec | +++ | 3.2 ± 0.38 | 89 |
| α with C-His tagc | +++ | 2.9 ± 0.30 | 87 |
| Null controlc | - | ≤0.01 | 0 |
a
Measured at 30°C and expressed as μmol ATP hydrolysed/min/mg membrane protein.
b
Measured using acridine orange and expressed as per cent quench of acridine orange fluorescence in membrane vesicles upon addition of 1 mM MgATP.
c
Wild-type, pBWU13.4/DK8; α with C-His tag, pSWM132/DK8; Null control, pUC118/DK8. Data are means of six experiments obtained from two independent membrane preparations of each mutant, and are expressed as means ± standard deviation. (Null controls had negligible activity).