Table 1.
Thermodynamic parameters of RNase A and S, and Cyt c as a function of sucrose concentration determined by GdnHCl- and thermal-induced unfolding a
| Proteins | [Sucrose] (M) | Cm (M) | −m (kcal/mole/M) | ΔGu (kcal/mole) | ΔΔGu (kcal/mole) | Tm (°C) |
| RNase A | 0 | 3.04 ± 0.01 | 2.77 ± 0.01 | 8.46 ± 0.02 | — | 69.1 |
| 0.5 | 3.22 ± 0.02 | 2.74 ± 0.03 | 8.87 ± 0.10 | 0.41 ± 0.10 | 71.0 | |
| 1 | 3.53 ± 0.02 | 2.78 ± 0.10 | 9.84 ± 0.39 | 1.38 ± 0.39 | 72.7 | |
| RNase S | 0 | 1.03 ± 0.02 | 3.30 ± 0.08 | 3.56 ± 0.04 | — | 51.4 |
| 0.5 | 1.31 ± 0.04 | 3.20 ± 0.31 | 4.31 ± 0.43 | 0.75 ± 0.43 | 52.1 | |
| 1 | 1.63 ± 0.02 | 3.04 ± 0.06 | 5.00 ± 0.07 | 1.44 ± 0.08 | 56.2 | |
| Cyt c | 0 | 2.54 ± 0.03 | 3.70 ± 0.19 | 9.43 ± 0.43 | — | 85b |
| 0.5 | 2.69 ± 0.02 | 3.66 ± 0.12 | 9.76 ± 0.25 | 0.33 ± 0.50 | ||
| 1 | 2.93 ± 0.03 | 3.48 ± 0.23 | 10.22 ± 0.56 | 0.79 ± 0.71 | 89c |
Values represent the mean ± standard deviation for triplicate samples.
a ΔΔGu values were the differences in ΔGu values relative to that in 0 M sucrose, respectively.
b Onset temperature of thermal unfolding in 0 M sucrose.
c Onset temperature of thermal unfolding in 0.75 M sucrose.