Table 3. Thermodynamic Parameters of DNA Duplexes.

duplex	Tma (°C)	ΔH° (kcal/mol)	ΔS° (kcal/mol °K)d	ΔG°25 °C (kcal/mol)d	ΔG°37 °C (kcal/mol)d	ΔΔG37 °C (kcal/mol)d
T6•A19b	71.6	−87.3 ± 2	−0.23 ± 0.01	−18.1 ± 0.2	−15.2 ± 0.2
Tg6•A19b	58.3	−83.8 ± 1	−0.23 ± 0.01	−14.7 ± 0.1	−11.9 ± 0.1	3.3 ± 0.1
Tg6•G19 b	58.3	−87.5 ± 5	−0.24 ± 0.02	−15.0 ± 0.3	−12.1 ± 0.2	3.1 ± 0.2
T6•A19 c	73.4	−90.7 ± 2	−0.24 ± 0.02	−18.8 ± 0.2	−15.9 ± 0.2
Tg6•A19 c	60.5	−81.1 ± 2	−0.22 ± 0.04	−14.9 ± 0.4	−12.2 ± 0.4	3.0 ± 0.4
Tg6•G19 c	60.0	−86.4 ± 1	−0.24 ± 0.02	−15.3 ± 0.2	−12.5 ± 0.2	2.7 ± 0.2

^aCalculated for 1.0 × 10⁻⁴ M oligodeoxynucleotide duplex concentration.

^bReported errors are standard deviations.

^cDetermined from individual melting curves.

^dDetermined from (T_m⁻¹) vs ln(C_t/4) plots.