Table 2.
Thermodynamic parameters derived for the unfolding of WT*, SL1-ΔA35, SL1-ΔA35/U33C, SL1-ΔA35/C34U, and SL1-ΔA35/A36U RNAs
| RNA | Transition 1a |
Transition 2 |
||||
|---|---|---|---|---|---|---|
| ΔH1 | tmm1 | ΔH2 | tm2 | ΔGo37 | ΔΔGo37 | |
| WT* | 37.9 | 60.8 | 81.0 | 74.5 | − 11.5 | 3.0 |
| ΔA35 | 118.3 | 80.3 | – | – | − 14.5 | – |
| ΔA35/U33C | 37.9 | 60.8 | 85.7 | 76.7 | − 12.4 | 2.1 |
| ΔA35/C34U | 37.9 | 60.8 | 72.0 | 72.2 | − 10.0 | 4.5 |
| ΔA35/A36U | 37.9 | 60.8 | 69.8 | 72.2 | − 9.8 | 4.7 |
Enthalpy and free energy are reported in kilocalories per mole, and tm is reported in degrees Celsius. Thermodynamic parameters derived from the optical melting profiles determined using the two-state van't Hoff unfolding model, with ΔCp = 0.22
Parameters for transition 1 were fixed to the predicted values for the unfolding of the bottom four base pairs of SL1, with transition 2 parameters optimized during the fit (see the text for details). The ΔG37,i for the ith individual transition was obtained from ΔGo37 = ΔH − 310.15 × ΔS, where ΔS = ΔH/tm. ΔGo37 = ∑ΔG37i, and ΔΔGo37 is expressed relative to the ΔGo37 measured for the SL1-ΔA35 RNA.