Table 3.
Rate constants for iron release from FeChTF and His349 FeChTF mutants in 100 mM MES, pH 5.6, containing 300 mM KCl and 4 mM EDTA
| Construct | Iron release k1 (min−1)a | Fold difference control | Conformational event k2 (min−1) | Fold difference control |
|---|---|---|---|---|
| FeChTF controlb (N = 6) | 0.79 ± 0.11 | – | 1.9 ± 0.50 | – |
| H349A FeChTF (N = 4) | 0.87 ± 0.10 | 1.1 × faster | 1.4 ± 0.14 | 0.8 × slower |
| H349D FeChTFc (N = 3) | 0.60 ± 0.15 | 1.3 × slower | 0.95 ± 0.31 | 2 × slower |
| H349K FeChTF (N = 7) | 1.04 ± 0.29 | 1.3 × faster | 1.8 ± 0.67 | 1.1 × slower |
| H349L FeChTF (N = 3) | 0.73 ± 0.11 | 0.9 × slower | 2.1 ± 0.66 | 1.1 × faster |
| H349W FeChTFc (N = 3) | 0.38 ± 0.01 | 2.1 × slower | 1.8 ± 0.48 | 0.9 × slower |
| H349Y FeChTFc (N = 3) | 0.54 ± 0.07 | 1.5 × slower | 2.6 ± 1.2 | 1.4 × faster |
a
Averages and 95% confidence intervals for kinetic runs performed on N = 3–7 different days. Each day three kinetic traces were averaged before fitting
b
From [6]
c
Note that under the stated conditions, we estimate that only approximately 50% of the iron is removed from the H349D and H349W mutants and that approximately 70% of the iron is removed from the H349Y mutant. These estimates are based on the steady-state data in Table 2