Table 2.
Steady-state kinetic parameters for tRNASecUX and tRNAUTu1 for wild-type SerRS and variants V8 and V20. The tRNASecUX and tRNAUTu1 concentrations were corrected for plateau charging (39 % and 55 %, respectively). For tRNASecUX serylation the enzyme concentrations were: 500 nM wild-type SerRS, 187 nM SerRS V8, 92 nM SerRS V20; for tRNAUTu1 the enzyme concentrations were: 150 nM wild-type SerRS, 34 nM SerRS V8, 34 nM SerRS V20, 224 nM SerRS V22.
| enzyme | KM (μM) | kcat (min−1) | kcat / KM (min−1 μM−1) | relative improvement | tRNA |
|---|---|---|---|---|---|
| wt | 3.7 | 0.14 | 0.038 | 1 | tRNASecUX |
| V8 | 4.9 | 1 | 0.21 | 5.5 | |
| V20 | 3.7 | 0.26 | 0.071 | 1.9 | |
| wt | 5.7 | 4.9 | 0.86 | 1 | tRNAUTu1 |
| V8 | 3.1 | 29 | 9.3 | 11 | |
| V20 | 2.7 | 13 | 4.9 | 5.7 |