Table 2.
Kinetic parameters of the E. coli YfbR (wild type and mutants) and wild type YfdR with various substrates.
| Protein | Variable substrate | Km, μM | Vmax, U/mga | kcat, s−1 | kcat/Km, M−1s−1 |
|---|---|---|---|---|---|
| YfbR (w.t.) | dAMP | 17.0 ± 3.0 | 0.36 ± 0.01 | 0.14 ± 0.004 | 8.09 × 103 |
| YfbR (V30A) | dAMP | 42.0 ± 5.0 | 0.22 ± 0.01 | 0.08 ± 0.004 | 1.98 × 103 |
| YfbR (V37A) | dAMP | 16.0 ± 2.0 | 0.35 ± 0.01 | 0.13 ± 0.004 | 8.41 × 103 |
| YfbR (E122A) | dAMP | 34.0 ± 3.0 | 0.16 ± 0.01 | 0.06 ± 0.004 | 1.72 × 103 |
| YfdR (w.t.) | dAMP | 118.9 ± 19.0 | 5.88 ± 0.35 | 2.28 ± 0.14 | 1.90 × 104 |
| dGMP | 64.7 ± 2.3 | 4.13 ± 0.05 | 1.60 ± 0.02 | 2.46 × 104 | |
| dUMP | 310.5 ± 37.6 | 3.51 ± 0.18 | 1.36 ± 0.07 | 0.44 × 104 | |
| dCMP | 78.5 ± 4.1 | 2.17 ± 0.04 | 0.84 ± 0.02 | 1.06 × 104 | |
| d™P | 129.4 ± 11.3 | 3.08 ± 0.10 | 1.19 ± 0.04 | 0.92 × 104 | |
| dIMP | 47.5 ± 4.2 | 1.56 ± 0.04 | 0.61 ± 0.02 | 1.27 × 104 | |
| GMP | 379.8 ± 23.6 | 1.78 ± 0.05 | 0.69 ± 0.02 | 1.82 × 102 | |
| Co2+ b | 340.0 ± 50.0 | 3.13 ± 0.19 | 1.21 ± 0.07 | 3.56 × 103 |
a
U/mg, μmoles/min mg protein
b
determined using 0.5 mM dAMP as substrate