Kinetic and thermodynamic parameters for the in vitro reaction between rxYFP and glutathione
pH . | Kox(M)a . | kox(M−1min−1)a . | kred(M−2min−1)b . |
|---|---|---|---|
| 6.1 | 11.8 ± 0.9 | 25.5 ± 0.6 | 2.2 ± 0.2 |
| 6.4 | 9.9 ± 0.3 | 32.6 ± 0.3 | 3.3 ± 0.1 |
| 6.7 | 8.2 ± 0.5 | 41.6 ± 0.7 | 5.0 ± 0.3 |
| 7.0c | 6.8 ± 0.2 | 71.7 ± 0.9 | 10.6 ± 0.4 |
| 7.3 | 7.2 ± 0.4 | 123.9 ± 0.5 | 17.2 ± 1.0 |
| 7.6 | 7.6 ± 0.2 | 205.9 ± 1.0 | 27.0 ± 0.8 |
| 7.9 | 6.8 ± 0.2 | 400.4 ± 4.4 | 59.0 ± 0.2 |
pH . | Kox(M)a . | kox(M−1min−1)a . | kred(M−2min−1)b . |
|---|---|---|---|
| 6.1 | 11.8 ± 0.9 | 25.5 ± 0.6 | 2.2 ± 0.2 |
| 6.4 | 9.9 ± 0.3 | 32.6 ± 0.3 | 3.3 ± 0.1 |
| 6.7 | 8.2 ± 0.5 | 41.6 ± 0.7 | 5.0 ± 0.3 |
| 7.0c | 6.8 ± 0.2 | 71.7 ± 0.9 | 10.6 ± 0.4 |
| 7.3 | 7.2 ± 0.4 | 123.9 ± 0.5 | 17.2 ± 1.0 |
| 7.6 | 7.6 ± 0.2 | 205.9 ± 1.0 | 27.0 ± 0.8 |
| 7.9 | 6.8 ± 0.2 | 400.4 ± 4.4 | 59.0 ± 0.2 |
Values are given as the mean ± SD (see Materials and methods).
Calculated as kox/Kox.
An E°′ value of −265 mV for rxYFP was calculated from the measured Kox at pH 7 and an E°′ value of −240 mV for the GSH/GSSG redox couple (Rost and Rapoport, 1964). This redox potential is in good agreement with that determined previously (Ostergaard et al., 2001).