TABLE 3.
Kinetic parameters of ScThrRS and its variants for tRNAThr (AGU) in aminoacylation reaction
| Enzyme | kcata | Kma | kcat/Km | Relative kcat/Km | Loss of catalytic efficiency |
|---|---|---|---|---|---|
| ×10−2 s−1 | μm | mm−1 s−1 | % | -fold | |
| WT | 2.8 ± 0.1 | 1.1 ± 0.1 | 24.7 | 100 | |
| R52F | NMb | NM | NM | NM | NM |
| R52A | 0.2 ± 0.1 | 2.0 ± 0.3 | 1.0 | 4.3 | 23.1 |
| R52D | NM | NM | NM | NM | NM |
| R52K | 1.7 ± 0.1 | 1.2 ± 0.2 | 13.6 | 54.8 | 1.8 |
| G145D | 0.30 ± 0.02 | 1.4 ± 0.2 | 2.2 | 8.7 | 11.4 |
| S308F | 0. 14 ± 0.01 | 1.8 ± 0.1 | 0.8 | 3.1 | 32.5 |
| G356N | NM | NM | NM | NM | NM |
| S457F | 0.15 ± 0.06 | 1.2 ± 0.1 | 1.2 | 5.0 | 20.0 |
| G458D | NM | NM | NM | NM | NM |
| R461H | NM | NM | NM | NM | NM |
| G604E | NM | NM | NM | NM | NM |
| P627L | NM | NM | NM | NM | NM |
| G685D | NM | NM | NM | NM | NM |
| C-Δ3 | 1.5 ± 0.2 | 1.4 ± 0.1 | 10.4 | 42.1 | 2.4 |
| C-Δ5 | 1.2 ± 0.2 | 1.3 ± 0.2 | 5.6 | 37.3 | 4.4 |
| C-Δ10 | 1.0 ± 0.1 | 1.5 ± 0.2 | 5.1 | 26.2 | 4.9 |
a The results are shown as the average of three independent trials ± S.D.
b NM, activity too low to be measured.