Table 1.

Thermodynamic parameters of heteroduplex formation between 2′-O-methyl RNA and oligoribonucleotides in 0.1 M NaCl, pH 7^a

2′-O-methyl RNA (5′→3′)	RNA (5′→3′)	Average of curve fits				$T_{\text{M}}^{-1}$ versus log(CT/4) plots
		−ΔH° (kcal/mol)	−ΔS° (eu)	−ΔG°37 (kcal/mol)	TMb (°C)	−ΔH° (kcal/mol)	−ΔS° (eu)	−ΔG°37 (kcal/mol)	TMb (°C)
CAUGGG	CCCAUG	61.6 ± 17.7	173.9 ± 56.1	7.72 ± 0.34	43.1	60.9 ± 1.5	172.3 ± 4.9	7.52 ± 0.01	42.1
ACAACCA	UGGUUGU	49.4 ± 2.7	139.1 ± 8.7	6.20 ± 0.13	34.9	42.7 ± 0.8	117.3 ± 2.6	6.31 ± 0.02	35.4
ACACCCA	UGGGUGU	51.5 ± 5.3	138.5 ± 16.7	8.52 ± 0.15	49.5	47.7 ± 1.5	126.9 ± 4.6	8.38 ± 0.04	49.5
ACAGCCA	UGGCUGU	54.4 ± 2.3	147.4 ± 6.9	8.70 ± 0.14	49.9	50.7 ± 0.8	135.7 ± 2.5	8.56 ± 0.02	49.9
ACCACCA	UGGUGGU	51.1 ± 3.1	137.0 ± 9.4	8.62 ± 0.18	50.2	47.4 ± 2.6	126.5 ± 8.1	8.50 ± 0.09	50.3
ACCGCCA	UGGCGGU	60.0 ± 3.2	158.3 ± 9.6	10.86 ± 0.23	61.1	57.7 ± 2.7	151.4 ± 8.2	10.69 ± 0.16	61.1
ACGACCA	UGGUCGU	53.5 ± 3.6	145.5 ± 11.1	8.40 ± 0.14	48.2	49.6 ± 1.3	133.3 ± 4.1	8.28 ± 0.03	48.3
ACGCCCA	UGGGCGU	54.4 ± 2.3	142.2 ± 7.1	10.32 ± 0.11	60.2	58.9 ± 1.7	155.9 ± 5.2	10.56 ± 0.10	59.8
ACGGCCA	UGGCCGU	57.5 ± 5.2	150.9 ± 15.9	10.71 ± 0.30	61.3	57.5 ± 1.7	151.0 ± 5.0	10.68 ± 0.10	61.1
ACGUACA	UGUACGU	52.5 ± 3.3	146.5 ± 10.5	7.09 ± 0.11	40.3	49.2 ± 1.6	135.8 ± 5.2	7.09 ± 0.02	40.5
ACGUGCA	UGCACGU	58.3 ± 1.5	158.4 ± 4.6	9.20 ± 0.10	51.9	59.1 ± 1.4	160.8 ± 4.4	9.22 ± 0.05	51.8
ACGUUCA	UGAACGU	52.9 ± 0.43	147.9 ± 14.1	7.05 ± 0.14	40.1	47.2 ± 0.8	129.3 ± 2.7	7.09 ± 0.01	40.7
ACUACAU	AUGUAGU	46.5 ± 2.6	132.3 ± 8.7	5.41 ± 0.10	29.7	45.9 ± 1.7	130.4 ± 5.8	5.45 ± 0.07	29.9
ACUACUU	AAGUAGU	52.1 ± 1.9	149.3 ± 5.9	5.78 ± 0.10	32.6	46.9 ± 1.2	132.3 ± 4.1	5.91 ± 0.04	32.9
AUUACCA	UGGUAAU	47.8 ± 1.6	137.0 ± 5.2	5.34 ± 0.11	29.5	44.5 ± 1.3	125.8 ± 4.5	5.47 ± 0.05	29.8
CGGCAUG	CAUGCCG	69.0 ± 3.6	191.7 ± 11.1	9.59 ± 0.15	51.4	65.5 ± 1.1	180.7 ± 3.6	9.48 ± 0.04	51.6
CUUACCA	UGGUAAG	54.9 ± 3.8	154.7 ± 12.1	6.89 ± 0.08	39.0	50.2 ± 0.8	139.6 ± 2.6	6.68 ± 0.01	39.1
GCUAAGG	CCUUAGC	66.5 ± 6.4	188.2 ± 20.7	8.15 ± 0.11	44.7	71.1 ± 2.0	202.0 ± 6.4	8.17 ± 0.04	44.3
GUUACCA	UGGUAAC	55.3 ± 3.5	156.0 ± 11.1	6.88 ± 0.10	39.0	49.9 ± 1.2	138.6 ± 3.9	6.85 ± 0.01	39.0
UUUACCA	UGGUAAA	43.2 ± 3.7	122.2 ± 12.4	5.27 ± 0.21	28.2	43.0 ± 2.1	121.7 ± 7.0	5.28 ± 0.11	28.3
CGAGCAAG	CUUGCUCG	76.3 ± 8.9	213.2 ± 27.6	10.15 ± 0.35	52.4	70.8 ± 4.4	196.0 ± 13.7	10.01 ± 0.17	53.0
CGUUGAAG	CUUCAACG	67.1 ± 11.5	190.3 ± 36.9	8.09 ± 0.09	44.4	76.4 ± 13.1	219.6 ± 41.4	8.27 ± 0.39	44.2
GAGUGAAG	CUUCACUC	78.3 ± 5.1	22.6 ± 16.1	9.33 ± 0.21	48.5	79.6 ± 5.9	226.4 ± 18.8	9.37 ± 0.18	48.5
AGAAGUAAG	CUUACUUCU	84.5 ± 6.8	245.0 ± 22.4	8.49 ± 0.11	44.4	85.6 ± 7.6	248.5 ± 24.1	8.49 ± 0.17	44.3
CCAAGAUUG	CAAUCUUGG	94.2 ± 4.9	271.6 ± 15.3	9.95 ± 0.23	48.7	92.5 ± 5.8	266.4 ± 18.2	9.89 ± 0.17	48.7
CGAAAGAUG	CAUCUUUCG	78.3 ± 3.4	223.9 ± 10.6	8.87 ± 0.12	46.6	75.8 ± 1.6	216.2 ± 5.0	8.80 ± 0.02	46.6
GAAGAUUCG	CGAAUCUUC	79.1 ± 5.1	225.3 ± 16.0	9.21 ± 0.22	47.9	76.1 ± 6.6	216.1 ± 20.8	9.11 ± 0.21	47.9
GAUGUAAGU	ACUUACAUC	81.7 ± 8.4	235.1 ± 26.7	8.76 ± 0.25	45.7	79.9 ± 7.4	229.6 ± 23.7	8.71 ± 0.19	45.7
GGAAUGUAG	CUACAUUCC	87.0 ± 4.8	247.7 ± 14.9	10.19 ± 0.24	50.6	79.9 ± 13.0	225.5 ± 40.6	9.98 ± 0.56	51.0
Non-two-state duplex
CGAAGUGAA	UUCACUUCG	96.6 ± 6.1	277.6 ± 19.1	10.56 ± 0.23	50.5	77.2 ± 2.4	216.8 ± 7.6	9.99 ± 0.07	51.5

^aSolutions are 100 mM NaCl, 20 mM sodium cacodylate and 0.5 mM Na₂EDTA, pH 7.

^bCalculated for 10⁻⁴ M total strand concentration.