TABLE 4.
Rate and equilibrium constants for O2 and CO binding to position 86(G12) and 55(E18) mutants of CerHb at pH 7.0, 20 °C
| CerHb | k′O2 | kO2 | KO2 | k′CO | kCO | KCO | KCO/KO2 |
|---|---|---|---|---|---|---|---|
| μm−1s−1 | s−1 | μm−1 | μm−1s−1 | s−1 | μm−1 | ||
| Ala-55/Leu-86 (wt)a | 230 ± 17 | 190 ± 25 | 1.2 ± 0.2 | 32 ± 5 | 0.054 ± 0.005 | 590 ± 100 | 490 ± 110 |
| Ala-86 | 230 | 153 | 1.5 | 30 | 0.053 | 570 | 380 |
| Phe-86 | 120 | 71 | 1.7 | 24 | 0.024 | 710 | 600 |
| Trp-86 | 97 | 60 | 1.6 | 16 | 0.014 | 1100 | 700 |
| Trp-55 | 63 | 66 | 0.95 | 15 | 0.029 | 500 | 520 |
a The numbers for wt CerHb are based on the average of all determinations for the past 6 years (≥10 separate preparations).