Table 1.
Solute-functional group interaction potentials (α-values) and local solute partition coefficients (Kp) by surface type or ion for proline, glycine betaine, and urea.
| Surface Type (i) | 104αi, (m−1·Å−2) | Partition Coefficient (Kp) a | ||||
|---|---|---|---|---|---|---|
| Proline | GB39 | Urea19,17 | Proline | GB | Urea | |
| Aliphatic C | 5.3±1.3 | 3±3 | −1.1±0.5 | 0.85±0.04 | 0.92±0.08 | 1.03±0.02 |
| Aromatic C | −9.2±0.9 | −23±4 | −8.9±0.5 | 1.26±0.03 | 1.62±0.11 | 1.28±0.02 |
| Hydroxyl O | −0.7±1.3 | 1±2 | −2.5±0.6 | 1.02±0.04 | 0.97±0.06 | 1.08±0.02 |
| Amide O | 14.5±4.5 | 28±10 | −8.5±1.8 | 0.59±0.13 | 0.24±0.27 | 1.28±0.06 |
| Amide N | −11.8±3.2 | −20±7 | −3.7±1.6 | 1.33±0.09 | 1.54±0.19 | 1.10±0.07 |
| Carboxyl O | 16.6±4.3 | 29±2 | −3.7±1.6 | 0.53±0.12 | 0.22±0.06 | 1.13±0.05 |
| Phosphate O | 18.0±5.2 | 49±4 | −5.8±1.2 | 0.49±0.15 | 0.00 | 1.18±0.04 |
| Cationic N | −12.6±4.3 | −12±4 | 1.6±1.7 | 1.36±0.12 | 1.32±0.11 | 0.94±0.05 |
| Ionic Species (ion) | 102×βion, (m−1) | |||||
| Na+ | −4±4 | 0 b | 10±1 | |||
| K+ | −2±4 | 5±2 | 14±2 | |||
| Cl | 4±4 | −4±4 | −16±2 | |||
a
Kp calculated from the corresponding α-value using Eq. 5 and b1 =0.18 H2O Å−2 for the local water of hydration of these functional groups, as determined previously28,29, except for phosphate for which a minimum b1 =0.27 H2O Å−2 was determined previously 39
b
βion for the Na-GB interaction was set to zero.39