TABLE 2.
Calorimetrically-derived thermodynamic parameters for the formation of the 15-bp duplexes nonmodified or containing a single, site-specific 1,3-GNG intrastrand cross-link of transplatin at 4°C
| ΔH†
|
ΔS†
|
ΔG4°C†
|
K‡
|
||
|---|---|---|---|---|---|
| Duplex* | kcal/mol duplex | cal/K·mol duplex | kcal/mol duplex | M−1 | n‡ |
| TGTGT(15) | −64.9 | −193 | −11.5 | 8.57 × 108 | 1.07 |
| TGTGT(15) · transPt | −47.9 (17) | −144 (49) | −8.0 (3.5) | 3 × 106 | 1.01 |
| CGCGC(15) | −55.4 | −165 | −9.7 | 5.7 × 107 | 1.09 |
| CGCGC(15) · transPt | −48.0 (7.4) | −145 (20) | −7.8 (1.9) | 1.5 × 107 | 1.01 |
The ΔH and ΔS values are averages derived from three independent experiments. The experimental uncertainties of the parameters are as follows: ΔH (2%), ΔS (3%), ΔG4 (3%). “ΔΔ” parameters are in parentheses (these parameters are computed by subtracting the appropriate value measured for the control, unmodified duplex from the value measured for the duplex containing a single, site-specific transplatin adduct).
G's in bold represent platinated guanine residues.
ΔH, ΔS, and ΔG4 denote, respectively, the enthalpy, entropy, and free energy (at 4°C) of duplex formation.
K and n denote, respectively, the association constant and binding stoichiometry for strand association.