Table 4. Thermodynamic Parameters of Oligos with A3 Enzymes Obtained by ITCa.
| oligo | protein | ITC bufferb | Kd (μM) | ΔH(kcal/mol) | TΔS(kcal/mol) |
|---|---|---|---|---|---|
| 5′-AT3CAT3 | A3A-E72A | 1 | 0.20 ± 0.04 | –22.9 ± 1.2 | –13.4 ± 1.2 |
| 5′-T4CAT | A3A-E72A | 1 | 0.27 ± 0.04 | –19.8 ± 0.9 | –13.1 ± 0.9 |
| dC-9-mer-X | A3A-E72A | 1 | 0.63 ± 0.13 | –18.1 ± 0.9 | –9.7 ± 0.9 |
| dC-7-mer-X | A3A-E72A | 1 | 0.48 ± 0.10 | –14.1 ± 1.4 | –5.4 ± 1.4 |
| dC-5-mer-X | A3A-E72A | 1 | 4.5 ± 0.9 | –10.9 ± 1.2 | –3.8 ± 1.1 |
| 5′-AT3CAT3 | A3A-E72A | 2 | 0.15 ± 0.03 | –53 ± 3 | –44 ± 3 |
| 5′-T4CAT | A3A-E72A | 2 | 0.75 ± 0.15 | –45 ± 2 | –36 ± 2 |
| dC[UE(−2), AN3(+1)]X | A3A-E72A | 2 | 0.030 ± 0.006 | –67 ± 3 | –57 ± 4 |
| dZ-linear | A3BCTD-QM-ΔL3-AL1swap | 3 | 11.4 ± 2.3 | –13.0 ± 0.6 | –6.2 ± 0.6 |
| dZ[UE(−2), AN3(+1)]X | A3BCTD-QM-ΔL3-AL1swap | 3 | 2.5 ± 0.5 | –24.6 ± 1.2 | –16.7 ± 1.7 |
a
Kd is the dissociation constant for the ligand from A3; ΔH and TΔS are for association of the ligand to A3; the temperature is 25°C.
b
ITC buffer 1: 50 mM MES, pH 6.0, 100 mM NaCl, 200 μM EDTA, and 1 mM β-mercaptoethanol; ITC buffer 2: 50 mM Na+/K+ phosphate, pH 6.0, 50 mM NaCl, 50 mM choline acetate, 2.5 mM TCEP, and 200 μM EDTA with 30 mg/mL bovine serum albumin; ITC buffer 3: 50 mM Na+/K+ phosphate, pH 6.0, 200 mM trimethylamine N-oxide dihydrate, and 2.5 mM TCEP, 200 μM EDTA.