Table 1.
Numerically determined pH-dependent exchange rates for labile protons at 5.5 (2-hydrooxypropanamido group), 4.3 (amide group), 1.8 (secondary hydroxyl group) and 0.8 (primary hydroxyl groups) ppm. Data are shown in mean ± standard deviation. The relative labile proton ratio for 5.5, 4.3, 1.8 and 0.8 ppm was fixed to be 1:2:1:4, with labile proton ratio at 5.5 ppm determined to be 1:3449 ± 747.
| Ksw (s−1) | ksw (5.5 ppm) | ksw (4.3 ppm) | ksw (1.8 ppm) | ksw (0.8 ppm) |
|---|---|---|---|---|
| pH | ||||
| 5.5 | 47 ± 12 s−1 | 7 ± 4 s−1 | 388 ± 157 s−1 | 2070 ± 331 s−1 |
| 6 | 87 ± 34 s−1 | 17 ± 6 s−1 | 242 ± 188 s−1 | 1759 ± 519 s−1 |
| 6.5 | 265 ± 65 s−1 | 67 ± 15 s−1 | 416 ± 166 s−1 | 1856 ± 1567 s−1 |
| 7 | 1074 ± 298 s−1 | 190 ± 25 s−1 | 1104 ± 337 s−1 | 1715 ± 483 s−1 |
| 7.5 | 2896 ± 285 s−1 | 868 ± 260 s−1 | 9262 ± 6138 s−1 | 5117 ± 4485 s−1 |