Abstract
A nitro reductase system found predominantly in the liver and kidney of rabbit but also present to a small degree in other tissues, reduces chloramphenicol, p-nitrobenzoic acid and a variety of other aromatic nitro compounds to the corresponding amines. The nitro reductase system is found both in the soluble fraction of the cells and in microsomes. Either TPNH or DPNH can act as hydrogen donors but the former seems to be considerably more active. The system includes a flavoprotein whose prosthetic group can be replaced by FMN, FAD or riboflavin. An added excess of flavins accelerates the normal rate of reduction, perhaps by acting as an artificial electron carrier between the reduced pyridine nucleotide and the substrate.
Failure to require cysteine, glutathione, or manganese ions, and to be inhibited by aureomycin and other chelating agents, as well as its complete inhibition by oxygen shows that the mammalian system differs from the bacterial system of Escherichea coli.
There is considerable species difference in the activity of the reductase, the enzyme being highly active in mice, guinea pigs and rabbits and less so in rats and dogs.
Footnotes
- Received August 8, 1956.
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