Table 1.
Thermodynamic parameters for thermal denaturation of yeast frataxin variants. Effect of functional mutations on the protein thermal stability and iron binding affinity.
| Protein | ΔH (kJ.mol−1) | ΔGa (J.mol−1) | Tm (°C) | ΔTm (°C) | Δ(ΔG)b (J.mol−1) | Kd (μM)c |
|---|---|---|---|---|---|---|
| Wild Type | 118.0 ± 1.3 | 5946.7 | 40.4 ± 0.1 | - | - | 10.4 ± 2.1 |
| N122K | 145.6 ± 2.1 | 7772.2 | 44.7 ± 0.1 | + 4.3 ± 0.2 | 2286.6 | 11.0 ± 3.8 |
| N122A | 125.9 ± 1.7 | 4106.2 | 35.9 ± 0.1 | − 4.5 ± 0.2 | −2461.5 | 14.0 ± 1.0 |
| K123T | 120.1 ± 1.7 | 6197.8 | 41.0 ± 0.1 | + 0.6 ± 0.2 | 323.0 | 18.8 ± 2.4 |
| Q124A | 143.5 ± 1.3 | 5366.0 | 39.0 ± 0.1 | − 1.4 ± 0.2 | 758.1 | 13.2 ± 3.8 |
| N122A/K123T/Q124A | 90.8 ± 1.3 | 5863.5 | 40.2 ± 0.1 | − 0.2 ± 0.2 | 107.9 | 27.1 ± 1.0 |
| 101/103A | 230.5 ± 3.3 | 11001.4 | 52.0 ± 0.1 | + 11.6 ± 0.2 | 6030.4 | 20.9 ± 0.6 |
| 86/90/93A | 214.6 ± 3.8 | 11546.2 | 53.2 ± 0.1 | + 12.8 ± 0.2 | 6630.0 | 21.3 ± 1.0 |
| 86/90/93/101/103 A | 322.6 ± 6.3 | 16687.9 | 64.2 ± 0.1 | + 23.8 ± 0.2 | 11925.2 | 22.8 ± 0.9 |
a
ΔG at 25°C, considering an estimate for ΔCp of 50.2 J/mol/K.
b
Δ(ΔG) =[Δ(Tm)] × ΔSm = [Δ(Tm)] × (ΔHm/Tm), where ΔSm and ΔHm are values for the wild type.
c
(n=2)