Table 1. Thermodynamic parameters for duplex formation determined from UV melting and DSC measurements^a,b.

Duplex	UV melting	DSC
	Tm (°C)	Tm (°C)	ΔH° (kcal mol−1)	ΔS° (cal mol−1 K−1)	ΔG° (37°C) (kcal mol−1)
RNA1:RNA2	66.2 ± 0.2	53.9 ± 1.3	−85.2 ± 3.1	−263.2 ± 9.7	−3.58 ± 0.37
thioRNA1:RNA2	74.5 ± 0.3	66.9 ± 0.1	−100.8 ± 0.9	−299.4 ± 2.8	−7.90 ± 0.21
thioRNA1:thioRNA2	>99	91.0 ± 0.6	−126.9 ± 1.0	−350.8 ± 3.2	−18.1 ± 0.1
RNA1:DNA1	51.6 ± 0.1	43.9 ± 0.2	−87.8 ± 2.2	−279.5 ± 9.8	−0.98 ± 0.99
thioRNA1:DNA1	45.5 ± 0.9	35.9 ± 0.1	−61.7 ± 2.2	−200.8 ± 14.3	3.31 ± 0.37

^aErrors reflect standard deviation from three independent experiments.

^bExperimental conditions are described in Materials and Methods.