TABLE 2.
Substrate specificity of RdxA and FrxA nitroreductases
| Substrate | Sp act (μmol/min/mg of protein)a
|
|
|---|---|---|
| RdxA nitroreductase | FrxA nitroreductase | |
| MTZ | 5.13 | <0.0002 |
| NADPH (MTZ)b | 9.01 | <0.0002 |
| NTZ | 13.4 | 22.2 |
| Nitrofurazone | <0.0002 | 0.50 |
| Furazolidone | <0.0002 | 1.50 |
| Nitrofurantoin | <0.0002 | 2.01 |
a
Specific activities are calculated as the means for five assays of each of two independent batches of enzyme for FrxA and RdxA. The error in these assays is <15%.
b
NADPH oxidation was followed at 340 nm with MTZ as the electron acceptor.