Table 5.
Thermal stability of HARS enzymes with substrates
| Enzyme | Tm °C | Δ Tm °Ca | Δ Tm °Cb |
|---|---|---|---|
| WT | 51.7 ± 0.4c | - | |
| WT + histidine | 58.8 ± 0.4 | 7.0 | - |
| WT + ATP | 53.8 ± 0.2 | 2.0 | - |
| WT + tRNAHis | 53.4 ± 0.4 | 1.7 | - |
| Y454S | 46.3 ± 0.7c | - | −5.4 |
| Y454S + histidine | 54.4 ± 0.5 | 8.1 | −4.4 |
| Y454 + ATP | 47.0 ± 0.5 | 0.7 | −6.8 |
| Y454S + tRNAHis | 48.5 ± 0.4 | 2.2 | −4.9 |
| R362H | 44.1 ± 0.2c | - | −7.7 |
| R362H + histidine | 50.4 ± 0.4 | 6.3 | −8.4 |
| R362H + ATP | 48.2 ± 0.5 | 4.1 | −5.6 |
| R362H + tRNAHis | 51.3 ± 0.3 | 7.2 | −2.1 |
a
Relative to the apo form of the same enzyme.
b
Relative to the same form of WT HARS enzyme. Values reported are the mean ± standard error of 2 independent experiments in triplicate (1 experiment in triplicate for R362H).
c
Values that are significantly different WT to Y454S or R362H, p<0.0001 (extra sum-of-squares F test).