TABLE 2.

Substrate specificity of RdxA and FrxA nitroreductases

SubstrateSp act (μmol/min/mg of protein)a
RdxA nitroreductaseFrxA nitroreductase
MTZ5.13<0.0002
NADPH (MTZ)b9.01<0.0002
NTZ13.422.2
Nitrofurazone<0.00020.50
Furazolidone<0.00021.50
Nitrofurantoin<0.00022.01
  • 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.