Table 3.
pK values of histidyl residues in deoxy-Hb A and HbCO A in 0.1 M HEPES plus 0.1 M chloride in D2O at 29 °C.
| Site | pK (CO) | pK (deoxy) |
|---|---|---|
| α20 | 7.08 ± 0.01 | 7.02 ± 0.01 |
| α45 | 6.12 ± 0.02 | 5.25 ± 0.15 |
| α50 | 6.90 ± 0.02 | 7.14 ± 0.01 |
| α72 | 7.27 ± 0.01 | 7.47 ± 0.01 |
| α89 | 6.25 ± 0.03 | 6.80 ± 0.01 |
| α112 | 7.53 ± 0.01 | 7.49 ± 0.01 |
| β2 | 6.39 ± 0.01 | 6.17 ± 0.02 |
| β77 | 7.79 ± 0.01 | 7.46 ± 0.01 |
| β97 | 7.75 ± 0.02 | 8.01 ± 0.01 |
| β116 | 6.13 ± 0.05 | 6.35 ± 0.04 |
| β117 | 6.39 ± 0.02 | 6.43 ± 0.07 |
| β143 | 5.57 ± 0.06 | 4.70 ± 0.05 |
| β146 | 6.42 ± 0.03 | 7.93 ± 0.02 |
Reprinted with permission from ref. 12. Copyright 2004 American Chemical Society.