Table 2. Thermodynamic transition parameters for ferrochelatase, with or without porphyrin ligand, and Glu-289 variants.
The thermograms were obtained from protein samples in Bicine buffer. The heating rate was 1.0 °C/min, and in each case at least three measurements were performed. The uncertainties reported are the S.D. of the obtained values. Thermodynamic parameters were obtained from the analysis of the DSC curves with the ORIGIN MicroCal software (see the Experimental section for details). The model used allowed the calculation of the denaturation temperature, Tm, calorimetric enthalpy (ΔHcali) and van't Hoff Enthalpy (ΔHvHi). r is the calorimetric to van't Hoff enthalpy ratio. FC, wild-type ferrochelatase; MP, mesoporphyrin IX.
| Tm (°C) | ΔHcali (kJ·mol−1) | ΔHvHi (kJ·mol−1) | r | |
|---|---|---|---|---|
| FC | 56.0±0.3 | 477±5 | 403±3 | 1.2 |
| FC+MP* | 58.3±0.3 | 506±10 | 319±3 | 1.6 |
| E289A | 57.5±0.1 | 920±9 | 185±2 | 5.0 |
| E289Q | 61.0±0.2 | 565±6 | 194±2 | 2.9 |
* FC and MP were reacted in a 1:1 molar ratio.