Table 2.
Activation parameters for ht-ADH variants at pH 7, above the Arrhenius break
| Enzyme | ΔH‡, kcal/mol | TΔS‡, kcal/mol | Log(Aobs) |
| Wild type | 14.7 (±0.5) | −1.2 (±0.5) | 12.4 (±0.3) |
| L176V | 17.9 (±0.6) | 0.6 (±0.6) | 13.7 (±0.4) |
| L176A | 15.3 (±0.5) | −1.8 (±0.4) | 12.0 (±0.3) |
| L176G | 15.0 (±0.5) | −1.5 (±0.5) | 12.1 (±0.3) |
| L176Δ | 12.8 (±0.4) | −5.3 (±0.4) | 9.4 (±0.3) |
| V260A* | 13.6 (±1.0) | −3.3 (±0.9) | 10.9 (±0.6) |
*The breakpoint for this mutant is at 40 °C; the rest are at 30 °C. ΔH‡ is the enthalpy of activation, ΔS‡ is the entropy of activation, and Aobs is the observed Arrhenius prefactor, as defined in the text.