Table 2. Base-pair dissociation constants (Kop), base-pair lifetimes (τ0 = 1/kop) and lifetimes for base-pair opening (τ open = 1/kcl) of the WT, A9C, A9AC, A10G and A10CG pri-miR156a constructs determined by the Tris-catalyzed NMR exchange experiments at 23°Ca.
| Base pair | Imino | WT | A9C | A9AC | A10G | A10CG | |
|---|---|---|---|---|---|---|---|
| C15·G98 | G98 | Kop (×10–6) | 8.45 ± 1.12 | 3.27 ± 0.37 | 8.72 ± 0.61 | 9.09 ± 1.38 | 3.27 ± 0.77 |
| τ0 (ms) | 15.5 ± 2.4 | 8.3 ± 3.3 | 17.0 ± 1.1 | 24.0 ± 2.3 | 14.8 ± 6.4 | ||
| τopen (ns) | 131 ± 27 | 27 ± 11 | 148 ± 14 | 218 ± 64 | 48 ± 24 | ||
| kint (×106) | 4.06 ± 1.05 | 2.22 ± 0.26 | 0.76 ± 0.10 | 3.36 ± 0.86 | 2.73 ± 0.60 | ||
| U16·A97 | U16 | Kop (×10–6) | 20.6 ± 0.9 | 7.10 ± 0.30 | 19.2 ± 0.6 | 16.4 ± 1.7 | 6.07 ± 0.31 |
| τ0 (ms) | 5.0 ± 0.4 | 1.0 ± 0.7 | 4.4 ± 0.3 | 7.6 ± 0.6 | 1.6 ± 1.2 | ||
| τopen (ns) | 104 ± 9 | 7 ± 5 | 85 ± 7 | 124 ± 16 | 10 ± 8 | ||
| kint (×106) | 0.37 ± 0.05 | 1.24 ± 0.07 | 0.26 ± 0.03 | 1.95 ± 0.23 | 0.60 ± 0.06 | ||
| G17·C96 | G17 | Kop (×10–6) | 0.42 ± 0.18 | 0.28 ± 0.09 | 0.46 ± 0.10 | 0.31 ± 0.15 | 0.33 ± 0.13 |
| τ0 (ms) | 145 ± 115 | 287 ± 79 | 132 ± 42 | 340 ± 143 | 333 ± 139 | ||
| τopen (ns) | 61 ± 48 | 80 ± 33 | 61 ± 23 | 107 ± 72 | 110 ± 64 | ||
| kint (×106) | 0.41 ± 0.39 | 0.61 ± 0.49 | 0.57 ± 0.41 | 0.97 ± 0.69 | 0.97 ± 0.69 | ||
| A18·U95 | U95 | Kop (×10–6) | 4.68 ± 0.84 | 2.34 ± 0.26 | 5.00 ± 0.54 | 1.91 ± 0.95 | 2.69 ± 0.34 |
| τ0 (ms) | 18 ± 4 | 15 ± 4 | 21 ± 2 | 14 ± 6 | 21 ± 4 | ||
| τopen (ns) | 84 ± 22 | 36 ± 9 | 102 ± 14 | 26 ± 14 | 57 ± 14 | ||
| kint (×106) | 1.30 ± 0.39 | 2.73 ± 0.34 | 1.05 ± 0.24 | 6.06 ± 2.27 | 1.89 ± 0.32 | ||
| C19·G94 | G94 | Kop (×10–6) | 1.93 ± 0.29 | 0.89 ± 0.17 | 1.41 ± 0.26 | 1.01 ± 0.43 | 1.45 ± 0.29 |
| τ0 (ms) | 194 ± 11 | 220 ± 31 | 160 ± 14 | 180 ± 49 | 143 ± 17 | ||
| τopen (ns) | 375 ± 61 | 197 ± 48 | 225 ± 45 | 182 ± 92 | 207 ± 48 | ||
| kint (×106) | 0.52 ± 0.20 | 0.22 ± 0.17 | 0.80 ± 0.32 | 1.03 ± 0.43 | 0.97 ± 0.33 |
aParameters used in the calculation: kcoll = 1.5 × 109 s–1, pKa(G-NH1) = 9.24, pKa (U-NH3) = 9.20, pKa (Tris, 23°C) = 8.47; Sample condition: 100 mM NaCl. [Tris]total = 10–300 mM, 23°C. The pH of all samples and buffers was adjusted to 8.00 at 24.1°C and then calibrated to 8.03 at 23°C using the following equation: pH(23°C) = pH(24.1°C)−0.031 × (23–24.1). The errors for these values were determined from the curve fitting using Equation (6).