Table 2.

Thermodynamic Parameters for (CGA)₆ and Variants at pH 5.5 and 7.0

Thermodynamic Parameters, pH 5.5a
Sequence	Tm (°C)b	ΔG°37 (kcal/mol)	ΔH° (kcal/mol)	ΔS° (cal/mol K)	ΔΔG°37 (kcal/mol)c
(CGA)7	61	−15.6 ± 0.9	−107.9 ± 7.2	−298 ± 21	−3.8 ± 1.0
(CGA)6	60	−14.2 ± 0.7	−92.1 ± 3.1	−251 ± 9	−2.4 ± 0.8
(CGA)5	54	−11.8 ± 0.4	−75.8 ± 1.4	−207 ± 4	0
(CGA)4	43	−8.9 ± 0.2	−60.9 ± 3.5	−168 ± 11	2.9 ± 0.4
TGA(CGA)5	58	−13.4 ± 0.5	−85.6 ± 2.4	−233 ± 7	−1.6 ± 0.7
(CGA)5TGA	49	−10.3 ± 0.3	−65.8 ± 2.2	−179 ± 7	1.4 ± 0.5
(CGATGA)3	32	−6.9 ± 0.3	−59.7 ± 3.2	−171 ± 10	4.9 ± 0.5
(TGA)6	NA	NA	NA	NA	NA
GGA(CGA)5	56	−13.2 ± 0.7	−91.2 ± 2.6	−252 ± 8	−1.4 ± 0.8
(GAC)6	58	−13.3 ± 0.4	−85.8 ± 2.3	−234 ± 7	−1.5 ± 0.6
Thermodynamic Parameters, pH 7.0d
Sequence	Tm (°C)b	ΔG°37 (kcal/mol)	ΔH° (kcal/mol)	ΔS° (cal/mol K)	ΔΔG°37 (kcal/mol)
(CGA)6	55	−2.0 ± 0.2	−33.5 ± 1.1	−102 ± 3	9.8 ± 0.4

NA, not applicable.

^aThermodynamic parameters obtained at pH 5.5 are reported as averages of van’t Hoff analysis curve fitting results assuming bimolecular duplex formation, with oligomer concentrations between 1 and 120 × 10⁻⁶ M. Errors in ΔH° and ΔS° are reported as one SD from at least four concentrations, and error in δG°₃₇ is propagated as previously described (40, 41, 42).

^bT_m values are calculated for oligomer concentration of 3 × 10⁻⁶ M.

^cΔΔG°₃₇ for each sequence calculated with respect to (CGA)₅. Negative values represent a stabilized free energy of formation, whereas positive values represent destabilized free energy of formation.

^dThermodynamic parameters and T_m for pH 7.0 are reported as the average of four van’t Hoff curve fit data sets, assuming unimolecular hairpin formations, with oligomer concentrations between 1 and 10 × 10⁻⁶ M.