Table 5.
Sensitivity of 2-CysPrx WT and variants to inactivation by hyperoxidation
The initial rate in the TR/Trx system was determined with 50 μM cumene hydroperoxide (COOH). Data are means ±SD (n=3).
| 2-CysPrx | Initial rate (s–1 H2O2)b | Initial rate (s–1 COOH) | Overall limit of turnover | COOH concentration reducing turnover to half (mM) | Offset |
|---|---|---|---|---|---|
| WT | 0.23±0.01 | 0.44±0.01 | 193±35 | 0.17±0.11 | -5.5±51 |
| His6- | 0.26±0.00 | 0.34±0.01 | 230±19 | 0.27±0.07 | 105±20 |
| ΔC | 0.31±0.03 | 0.38±0.03 | >a | >a | >a |
| T92D | 0.14±0.01 | 0.18±0.01 | 73±12 | 1.47±0.37 | 20.0±2.3 |
| F84R | 0.14±0.01 | 0.19±0.01 | 74±10 | 0.95±0.17 | 4.1±1.3 |
a No inactivation but enhanced peroxidase activity of the ΔC-variant was observed.
b The initial rate was determined with 75 μM hydrogen peroxide.