Studies in the Enzyme Make-up of Salmonella typhosa*: Part IVƗ-Organic Nitro-reductase Activity

Abstract

A survey of the distribution of organic nitro-reductase in various antigenic strains of S. typhosa has been made. The enzyme system is not very specific as it reduces a number of aromatic nitro compounds to the corresponding arylamines, m-dinitrobenzene showing maximum reduction. The enzyme appears to be associated with the particulate fractions of the cells. The properties of the enzyme and the action of enzyme inhibitors have also been studied. Tetracyclines inhibit arylamine formation while penicillin, dihydrostreptomycin and neomycin have no significant effect. Hydroxylamine, iodoacetate, cyanide, semicarbazide and azide, nickel and zinc ions and the metal binders inhibit the enzyme activity.