Table 2.
Equilibrium and Rate Constants for Cyanide Binding to CcP(H52D), CcP(H52E), CcP(H52N), and CcP(H52Q)a
| Mutant | ka (M−1 s−1) | kd (s−1) | kd/ka = KDkin (M) | KD (M) |
|---|---|---|---|---|
| yCcPb | (1.1 ± 0.1) ×105 | 0.39 ± 0.05 | (3.6 ± 0.6) ×10−6 | (6 ± 3) ×10−6 |
| CcP(H52D) c | (1.9 ± 0.5) ×103 | 3.7 ± 0.2 | (1.9 ± 0.5) ×10−3 | (3.0 ± 0.7) ×10−3 |
| CcP(H52E) | (4.0 ± 0.1) ×103 | 0.36 ± 0.02 | (0.90 ± 0.06) ×10−4 | (1.0 ± 0.1) ×10−4 |
| CcP(H52N) | (9.4 ± 1.2) ×10−3 | |||
| fast | (3.4 ± 0.1) ×103 | 3.3 ± 0.1 | (0.97 ± 0.04) ×10−3 | |
| slow | (9 ± 2) ×102 | 0.3 ± 0.2 | (3 ± 2) ×10−3 | |
| CcP(H52Q) c | (8.4 ± 2.5) ×101 | (4.9 ± 0.5) ×10−2 | (5.8 ± 1.9) ×10−3 | (6.1 ± 0.8) ×10−3 |
a
pH 6.0, 0.10 M ionic strength with potassium phosphate buffer.
b
from reference [53].
c
The rate constants for the H52D and H52Q mutants are from the major phase of the cyanide binding reaction.