The 1-nitropyrene reductase of Salmonella typhimurium

We have devised a sensitive fluorimetric assay to monitor the conversion of 1-nitropyrene to 1-aminopyrene. Application of this assay to extracts of Salmonella typhimurium strains TA98 and TA100 (which are sensitive to the mutagenic and lethal effects of 1-nitropyrene) has shown that these bacteria contain 'nitropyrene reductase' activity at the low level of 10(-11) mol/min/mg protein. NADPH and NADH serve equally well as reducing agents. The nitropyrene reductase activity of strain TA100 F50 (a mutant resistant to 1-nitropyrene) was found to be considerably lower.