Table 3.
The kinetic parameters of wild-type SmTGR and Sec597Cys reacting with the substrates, DTNB (DTNB activity), GSSG (GR activity), and Trx (TrxR activity)
| DTNB activity (kcat, s−1) | % of WT | Km for DTNB (μM) | |
|---|---|---|---|
| WT | 16 ± 0.6 | - | 319 ± 47 |
| Sec597Cys | 4 ± 0.1 | 25a, 6.8b | 107 ± 10 |
| GR activity (kcat, s−1) | % of WT | Km for GSSG (μM) | |
| WT | 19 ± 1.2 | - | 42 ± 6 |
| Sec597Cys | 4 ± 0.6 | 21a, 5.7b | 71 ± 24 |
| TrxR activity (kcat, s−1) | % of WT | Km for Trx (μM) | |
| WT | 19 ± 1 | - | 8 ± 0.3 |
| Sec597Cys | 3.5 ± 0.1 | 18a, 4.9b | 15 ± 2.3 |
a
inhibition is determined by the activities of Sec597Cys compared to those of wild-type enzyme
b
inhibition is determined by the activities of Sec597Cys compared to those of wild-type enzyme when it is considered that only 27 % of wild-type enzyme is full length whereas 100 % of Sec597Cys is full length