4-Nitrobenzoic Acid Reductase of Ascaris lumbricoides var suum. Substrate Specificity and Reaction Products

Abstract

1. The substrate specificity of nitro reductase from Ascaris lumbricoides var suum was determined. This enzyme reduced nitrobenzene, 4-nitrohippuric acid and the isomers of nitrophenol, nitroanisole, nitrobenzoic acid, nitrobenzaldehyde and nitrobenzyl alcohol.

The same enzyme preparation reduced azobenzene, 4-dimethylaminoazobenzene and 1,2-dimethyl-4-(4-carboxyphenylazo)-5-hydroxybenzene. Nitrobenzaldehyde isomers were not reduced to the alcohols.

2. The products of nitro- and azo-reduction were the corresponding amines, no hydroxylamino or hydrazo compounds were detected.

3. The pH optima and cofactor requirements were the same for both azo- and nitro-reduction and neither reaction was inhibited by oxygen.

4. Ammonium sulphate fractionation failed to separate azo- and nitro-reductase activities. The molecular weight of both azo- and nitro-reductase was about 130 000.