TABLE 4.

Activity of purified lawsone reductase activity with nitrofurazone and effect of known NfsB inhibitors on enzyme activity^a

Inhibitor	Reductase activity (U mg of protein−1) with:
	Nitrofurazone (+ NADH)	Lawsone
		+ NADH	+ NADPH
None	20.6	33.7	17
Diphenyliodonium (50 μM)	8.6	6.3	4.7
Dicoumarol (50 μM)	0.1	0.1	0.1

^aThe reactions were performed under anaerobic conditions in a microtiter plate. The reaction mixtures contained in a total volume of 200 μl 50 mM Tris-HCl-buffer (pH 7.7), lawsone, or nitrofurazone (100 μM each) and the purified enzyme (0.5 mg of protein per ml). The reactions were started by the addition of NADH or NADPH (100 μM each), and the decrease in the absorbance was measured at 400 or 450 nm in a microtiter plate photometer.