Table 1.
Kinetic parameters of glutathione reductase activity and superoxide production by ToGR1 and ToGR2 in 100 mM phosphate buffer (pH 8.0)
| Enzyme | Activity | Substrate or product | kcat−1 (min−1) | Km (μM) | kcat Km,−1 (M−1 s−1) | kcat/kuncata |
|---|---|---|---|---|---|---|
| ToGR1 | Native | NADPH | 11,707 ± 671 | 11.7 ± 1.6 | (1.7 ± 0.1)×107 | 107.7 |
| GSH | 11,765 ± 676 | 13.0 ± 1.3 | (1.5 ± 0.1)×107 | 107.0 | ||
| Promiscuous | NADPH | 12.9 ± 1.0 | 23.3 ± 2.8 | 9626 ± 979 | 104.7 | |
| O2− | 10.0 ± 0.8 | 47.5 ± 4.1 | 3109 ± 289 | 104.1 | ||
| ToGR2 | Native | NADPH | 7692 ± 312 | 4.4 ± 0.5 | (3.0 ± 0.3)×107 | 107.5 |
| GSH | 7273 ± 243 | 5.0 ± 0.4 | (2.5 ± 0.1)×107 | 106.8 | ||
| Promiscuous | NADPH | 1.66 ± 0.13 | 82.7 ± 7.3 | 341 ± 47 | 103.9 | |
| O2− | 0.42 ± 0.11 | 210 ± 98 | 42 ± 11 | 102.7 |
Data represent the avg. ± std. err. of n = 3 (native activities), n = 8 (ToGR1 promiscuous) or n = 5 observations (ToGR2 promiscuous). All Km values are for NADPH.
a
Values for kuncat are listed in Table S2.