Table 2. Effects of ligands on the melting temperature of the fluorescently labelled oligonucleotides.
| Sequence | Thiazotropsin A | Distamycin | ||
|---|---|---|---|---|
| ΔTm with 10 μM | C50 (μM) | ΔTm with 10 μM | C50 (μM) | |
| ACTAGT | 8.0 | 11.2 ± 1.6 | 5.0 | 22.8 ± 2.1 |
| TGATCA | 1.1 | 175 ± 60 | 5.3 | 23.0 ± 2.7 |
| TGATCT | 0.4 | 210 ± 90 | 2.6 | * |
| TGTACT | 0.4 | 290 ± 150 | 2.1 | * |
| TGAACT | 0.2 | >300 | 3.0 | * |
| TCTAGT | 4.4 | 27 ± 3 | 1.5 | * |
| ATATAT | 6.0 | 20 ± 2 | 13.9 | 3.0 ± 0.4 |
| AAAAAG | 3.8 | 35 ± 3 | 15.0 | 0.9 ± 0.2 |
The second and fourth columns show the increase in melting temperature (ΔTm, °C) produced by addition of 10 μM of the ligands. C50 is the ligand concentration (μM) that produces half the maximal change in melting temperature and was obtained by fitting the data to the equation ΔTm = ΔTm,max × L/(L+C50), where ΔTm,max is the maximum change in melting temperature and L is the ligand concentration. These C50 values are only used to provide a convenient means for comparing the relative effects of the ligand on the different sequences, and do not have any direct physical meaning. Asterisks indicates that this equation did not fit the data, which showed a steady increase in melting temperature with increasing ligand concentration.