TABLE 1.
Calorimetrically derived thermodynamic parameters for dissociation (melting) of the 15-bp duplexes unmodified or containing a single, site-specific 1,2-GG intrastrand CL of cisplatin, [Pt(R,R-DACH)]2+, or [Pt(S,S-DACH)]2+
| TGGT(15) | Tm (°C) | ΔH (kcal/mol) | ΔS (cal/mol) |  |
|---|---|---|---|---|
| no Pt (control) | 58.9 | 96.8 | 294.1 | 9.1 |
| cisplatin | 48.7 | 63.0 (−33.8) | 196.7 (−97.4) | 4.4 (−4.7) |
| [Pt(R,R-DACH)]2+ | 48.1 | 59.9 (−36.9) | 187.3 (−106.8) | 4.1 (−5.0) |
| [Pt(S,S-DACH)]2+ | 45.3 | 56.7 (−40.1) | 178.4 (−115.7) | 3.5 (−5.6) |
| CGGA(15) | Tm (°C) | ΔH (kcal/mol) | ΔS (cal/mol) |  |
| no Pt (control) | 64.5 | 102.1 | 305.2 | 11.1 |
| cisplatin | 57.5 | 67.8 (−34.3) | 206.8 (−98.4) | 6.1 (−5.0) |
| [Pt(R,R-DACH)]2+ | 55.0 | 61.4 (−40.7) | 188.0 (−117.2) | 5.3 (−5.8) |
| [Pt(S,S-DACH)]2+ | 54.9 | 64.4 (−37.7) | 197.8 (−107.4) | 5.4 (−5.7) |
| AGGC(15) | Tm (°C) | ΔH (kcal/mol) | ΔS (cal/mol) |  |
| no Pt (control) | 62.1 | 99.8 | 300.2 | 10.3 |
| cisplatin | 55.8 | 84.2 (−15.6) | 257.7 (−42.5) | 7.4 (−2.9) |
| [Pt(R,R-DACH)]2+ | 53.9 | 72.2 (−27.6) | 221.9 (−78.3) | 6.0 (−4.3) |
| [Pt(S,S-DACH)]2+ | 53.9 | 73.6 (−26.2) | 226.6 (−73.6) | 6.0 (−4.3) |
The ΔH and ΔS values are averages derived from three independent experiments. The experimental uncertainties of the parameters are as follows: Tm (±0.5°C), ΔHcal (±2%), ΔS (±3%), 
(±3%). “ΔΔ” parameters are in parentheses (these parameters are computed by subtracting the appropriate value measured for control, unmodified duplex from the value measured for the duplex containing the single, site-specific platinum adduct).