Figure 5.

Exemplary isothermal titration calorimetry (ITC) experiments for unmodified (A) and 2′-SCF₃ modified (B) 14 bp RNA duplexes. Conditions: A 58 (A) and 165 (B) μM solution of lower strand was titrated into 0.3 mL of 4.1 (A) and 5.5 (B) μM upper strand equilibrated at 25 °C. Both RNAs were in 10 mM Na₂HPO₄, 150 mM NaCl, pH 7.0. The experiments depicted yielded fitting parameters as indicated. Unmodified RNA: ΔH = −116 ± 9 kcal mol⁻¹, ΔS = −356 ± 30 cal mol^–1 K^–1. 2′-SCF₃ RNA: ΔH = −106 ± 7 kcal mol⁻¹, ΔS = −323 ± 25 cal mol^–1 K^–1 (from at least two independent measurements).