Table 4. T_m values and thermodynamic data for oligonucleotide duplexes containing purin-2,6-diamine 2′-deoxyribonucleoside 1 and pyrazolo[3,4-d]pyrimidine analogs 2a,b^a.

	Tm (°C)	ΔG0310 (kcal/mol)
5′-d(TAG GTC AAT ACT) (12)
3′-d(ATC CAG TTA TGA) (13)	47	–10.6
5′-d(T1G GTC 11T 1CT) (14)
3′-d(ATC C1G TT1 TGA) (15)	50b	–
5′-d(TAG GTC 2a2aT ACT) (16)
3′-d(ATC C2aG TT2a TGA) (17)	51	–12.3
5′-d(TAG GTC AAT ACT) (12)
3′-d(ATC C1G TT1 TGA) (15)	49	–10.9
5′-d(TAG GTC AAT ACT) (12)
3′-d(ATC C2aG TT2a TGA) (17)	50	–12.1
5′-d(TAG GTC AAT ACT) (12)
3′-d(ATC C2bG TT2b TGA) (18)	59	–13.9
5′-d(TAG GTC 2b2bT ACT) (21)
3′-d(ATC CAG TT A TGA) (13)	56	–13.4
5′-d(TAG GTC 2b2bT ACT) (21)
3′-d(ATC C2bG TT 2bTGA) (18)	67	–17.0
5′-d(T2bGGTC2b2bT2bCT) (19)
3′-d(A TC CAG T T ATGA) (13)	64	–15.8
5′-d(TAG GTC AAT ACT) (12)
3′-(AUC CAG UUA UGA) (20)	45	–10.2
5′-d(T1G GTC 11T 1CT) (14)
3′-(AUC CAG UUA UGA) (20)	48	–10.2
5′-d(TAG GTC 2a2aT ACT) (16)
3′-(AUC CAG UUA UGA) (20)	48	–
5′-d(TAG GTC 2b2bT ACT) (21)
3′-(AUC CAG UUA UGA) (20)	53	–12.7

^aMeasured at 260 nm in 0.1 M NaCl, 10 mM MgCl₂ and 10 mM Na cacodylate buffer, pH 7.0, with 5 µM + 5 µM single strand concentrations.

^bLow cooperativity.

^cNot measured.