Table 1.
The kinetic and equilibrium parameters characterizing the dynamics of proton transfer between bulk and the surface of cytochrome oxidase
| pH | 6.82 | 7.1 | 7.31 | 7.7 |
| pK(Flu) | 7.55 | 7.55 | 7.55 | 7.55 |
| pK(BufferEC) n = 12 | 4.85 | 4.85 | 4.85 | 4.85 |
| pK(COO−near) n = 1 | 5.05 | 5.05 | 5.05 | 5.05 |
| pK(Hisnear) n = 1 | 6.35 | 6.35 | 6.35 | 6.35 |
| pK(COO−av) n = 15 | 4.4 | 4.4 | 4.4 | 4.4 |
| pK(Hisav) n = 10 | 6.35 | 6.35 | 6.35 | 6.35 |
| Flu + H+ | 1.5 ± 0.25 E 10 | 1.75 ± 0.25 E 10 | 1.5 ± 0.25 E 10 | 1.5 ± 0.25 E 10 |
| Buffer−EC + H+ | 2.0 ± 0.3 E 10 | 1.5 ± 0.3 E 10 | 2.0 ± 0.3 E 10 | 1.75 ± 0.3 E 10 |
| Flu + φO− | 1.0 ± 0.05 E 9 | 1.0 ± 0.05 E 9 | 1.0 ± 0.05 E 9 | 1.0 ± 0.05 E 9 |
| COO−near + H+ | 2.0 ± 0.3 E 10 | 2.0 ± 0.3 E 10 | 1.5 ± 0.3 E 10 | 1.5 ± 0.3 E 10 |
| COO−near + Flu | 1.0 ± 0.1 E 12 | 0.7 ± 0.1 E 12 | 0.4 ± 0.1 E 12 | 0.25 ± 0.1 E 12 |
| Hisnear + H+ | 0.5 ± 0.4 E 10 | 0.5 ± 0.4 E 10 | 0.5 ± 0.4 E 10 | 0.5 ± 0.4 E 10 |
| Hisnear + Flu | 3.5 ± 0.3 E 10 | 1.5 ± 0.25 E 10 | 1.2 ± 0.25 E 10 | 0.3 ± 0.3 E 10 |
| Hisnear + COOnear | 0.5 ± 0.4 E 10 | 0.5 ± 0.4 E 10 | 0.5 ± 0.4 E 10 | 0.5 ± 0.4 E 10 |
| COO−av + H+ | 3.0 ± 0.5 E 10 | 3.0 ± 0.5 E 10 | 3.0 ± 0.5 E 10 | 3.0 ± 0.5 E 10 |
| COO−av + Flu | <1.0 E 7 | <1.0 E 7 | <1.0 E 7 | <1.0 E 7 |
| COO−av + COOnear | <1.0 E 9 | <1.0 E 9 | <1.0 E 9 | <1.0 E 9 |
| COO−av + Hisnear | <1.0 E 9 | <1.0 E 9 | <1.0 E 9 | <1.0 E 9 |
| Hisav + H+ | 1.0 ± 0.3 E 10 | 1.0 ± 0.3 E 10 | 1.0 ± 0.3 E 10 | 1.0 ± 0.3 E 10 |
| Hisav + Flu | 5.0 ± 0.5 E 8 | 5.0 ± 0.5 E 8 | 5.0 ± 0.5 E 8 | 5.0 ± 0.5 E 8 |
| Hisav + φOH | 3.5 ± 0.2 E 8 | 4.0 ± 0.2 E 8 | 3.5 ± 0.2 E 8 | 1.1 ± 0.2 E 8 |
| Hisav + COO−near | 2.0 ± 0.5 E 10 | 2.0 ± 0.5 E 10 | 1.0 ± 0.5 E 10 | 1.0 ± 0.5 E 10 |
| Hisav + Hisnear | 7.5 ± 0.25 E 9 | 7.5 ± 0.25 E 9 | 7.5 ± 0.25 E 9 | 7.5 ± 0.25 E 9 |
| Hisav + COO−av | 2.5 ± 0.5 E 10 | 3.0 ± 0.5 E 10 | 4.0 ± 0.5 E 10 | 4.0 ± 0.5 E 10 |
n, number of reactive groups in each type of reactants.
The bold face lines denote the reactions which are the main pace makers of the overall process; the italic lines denote the reactions between reactants bound to the surface and the rate constants are of virtual second order reactions.