Table 1.
Equilibrium binding constants (KD), relative thiazole orange (TO) displacement ratio (%) and stabilization temperatures (ΔTm) of the synthesized compounds.
| Comp. | KD (μM) 1 | TO (%) 2 | ΔTm (°C) 3 | Comp. | KD (μM) | TO (%) | ΔTm (°C) | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Py24 | Pu24 | Duplex | Py24 | Py24 | Py24 | Pu24 | Duplex | Py24 | Py24 | ||
| OA-His | 13.3 | >50 4 | >50 | n.d. 5 | 6.2 | 4g | >50 | >50 | >50 | n.d. | n.d. |
| 3b | 11.4 | >50 | >50 | 27% | 1.0 | 4h | >50 | >50 | >50 | n.d. | n.d. |
| 3c | 1.95 | >50 | >50 | 67% | 19.1 | 4i | >50 | >50 | >50 | n.d. | n.d. |
| 3d | 12.1 | >50 | >50 | 13%. | −1.6 | 4j | >50 | >50 | >50 | n.d. | n.d. |
| 3e | 13.8 | >50 | >50 | 20% | 0.6 | 4k | 12.3 | >50 | >50 | 15% | 3.3 |
| 3f | >50 | >50 | >50 | n.d. | n.d. | 4l | >50 | >50 | >50 | n.d. | n.d. |
| 3g | >50 | >50 | >50 | n.d. | n.d. | 4m | 10.6 | >50 | >50 | 24% | 1.8 |
| 3h | 3.09 | >50 | >50 | 37% | 0.5 | 4n | >50 | >50 | >50 | n.d. | n.d. |
| 3i | 5.01 | >50 | >50 | 51% | 7.0 | 4o | 12.0 | >50 | >50 | 25% | 0.1 |
| 3j | >50 | >50 | >50 | n.d. | n.d. | 8a | >50 | >50 | >50 | n.d. | n.d. |
| 3k | >50 | >50 | >50 | n.d. | n.d. | 8b | 31.3 | >50 | >50 | 10% | −0.3 |
| 3l | >50 | >50 | >50 | n.d. | n.d. | 8c | 21.1 | >50 | >50 | 5% | 0.2 |
| 3m | >50 | >50 | >50 | n.d. | n.d. | 8d | >50 | >50 | >50 | n.d. | n.d. |
| 3n | >50 | >50 | >50 | n.d. | n.d. | 8e | >50 | >50 | >50 | n.d. | n.d. |
| 3o | >50 | >50 | >50 | n.d. | n.d. | 8f | >50 | >50 | >50 | n.d. | n.d. |
| 3p | >50 | >50 | >50 | n.d. | n.d. | 8g | >50 | >50 | >50 | n.d. | n.d. |
| 3q | >50 | >50 | >50 | n.d. | n.d. | 8h | >50 | >50 | >50 | n.d. | n.d. |
| 4a | 19.3 | >50 | >50 | 19% | 1.8 | 9 | >50 | >50 | >50 | n.d. | n.d. |
| 4b | 13.0 | >50 | >50 | 16% | 1.9 | 10a | >50 | >50 | >50 | n.d. | n.d. |
| 4c | >50 | >50 | >50 | n.d. | n.d. | 10b | >50 | >50 | >50 | n.d. | n.d. |
| 4d | >50 | >50 | >50 | n.d. | n.d. | 10c | >50 | >50 | >50 | n.d. | n.d. |
| 4e | >50 | >50 | >50 | n.d. | n.d. | 10d | >50 | >50 | >50 | n.d. | n.d. |
| 4f | >50 | >50 | >50 | n.d. | n.d. | ||||||
1KD values were determined by using surface plasmon resonance (SPR) experiments. 2 Relative TO displacement ratio (%) was determined at a fixed i-motif concentration (1 μM) either with or without a fixed concentration (5 μM) of compounds. 3 temperature enhancements (ΔTm) were determined using circular dichroism (CD)-melting experiments. ΔTm = Tm (DNA + ligand) − Tm (DNA). 4 No significant binding affinity was observed upon the addition of up to 50 μM compounds. 5 “n.d.” means not determined.