Oxygen--insensitive nitrofuran reductases in Salmonella typhimurium TA100

The present study demonstrated by DEAE-cellulose column chromatography that oxygen-insensitive nitrofuran reductases in Salmonella typhimurium TA100 consisted of at least two reductases, NADPH- and NAD(P)H-linked enzymes. The NADPH- and NADH-linked activities of the latter enzyme seemed to originate from a single enzyme, because both activities were similarly inactivated by heat and urea treatments, and also inhibited by dicumarol. On the other hand, the NADPH-linked enzyme was less sensitive to heat, urea and dicumarol. Furthermore, the study showed that the NAD(P)H-linked enzyme was a flavoenzyme which could be inactivated by dialysis against 1 M potassium bromide and reactivated by FMN.