Table 2.
Activities of purified complex I reconstituted into proteoliposomes
| Strain | Treatmenta | Complex I activityb | Coupling ratioc | |
|---|---|---|---|---|
| −CCCP | +CCCP | |||
| µmol min-1 mg-1 | ||||
| Parental | – | 4.6 ± 1.1 | 12.5 ± 1.9 | 2.7 |
| DTT | 4.9 ± 1.4 | 13.1 ± 2.1 | 2.7 | |
| DTNB | 4.5 ± 1.5 | 11.8 ± 2.4 | 2.6 | |
| Q133CPSST | – | 8.4 ± 0.8 | 9.7 ± 0.5 | 1.2 |
| DTT | 4.8 ± 1.0 | 10.4 ± 0.4 | 2.2 | |
| DTNB | 8.1 ± 1.0 | 9.5 ± 0.4 | 1.1 | |
aProteoliposomes were incubated with 5 mM DTT or 0.1 mM DTNB for 5 min before oxidoreductase activity measurements. Three independent batches of proteoliposomes were analyzed. Data are given as mean ± s.d.
bDQA-sensitive NADH:DBQ oxidoreductase activities were measured in the absence or presence of 5 µM CCCP. To correct for variations in content and orientation of complex I in the proteoliposomes, values were normalized to their respective NADH:HAR oxidoreductase activities, which were 40 ± 1 µmol min-1 mg-1 and 35 ± 1 µmol min-1 mg-1 for parental and mutant Q133CPSST samples, respectively
cCoupling ratios were calculated by dividing the NADH:DBQ oxidoreductase activities in the presence of 5 µM CCCP by the activities in its absence