Table 2.
Activity of recombinant TbERV1 in comparison with that of site-directed mutants
| Enzyme | Substrate | Reduction (μM min−1 μM TbERV1−1) ofa: |
|
|---|---|---|---|
| O2 | Cytochrome c | ||
| WT TbERV1 | TCEP | 11.97 ± 3.3 | 19.92 ± 5.0 |
| DTT | 22.91 ± 3.7 | NDb | |
| Distal Cys pair mutant | TCEP | 30.03 ± 2.7 | 26.67 ± 1.5 |
| DTT | 30.43 ± 3.8 | NDb | |
| Proximal Cys pair mutant | TCEP | 0.38 ± 0.1 | 1.08 ± 1.9 |
| DTT | 0.14 ± 0.2 | NDb | |
| O2 channel mutant | TCEP | 7.24 | NDc |
| DTT | NDc | ||
a
Rates were determined using 3.5 mM electron donor under either aerobic conditions or under anaerobic conditions in the presence of 15 μM C. fasciculata cytochrome c. Errors are standard deviations from at least 3 independent measurements. The values for WT TbERV1 are similar to those quoted in Table 1; note that the Erv1 used for experiments summarized in Table 2 was purified, refolded, and assayed independently from the TbERV1 prepared for the experiments summarized in Table 1.
b
Not determined (ND) due to efficient reduction of cytochrome c by DTT.
c
Not determined due to a lack of protein (see the text).