TABLE 2.

Electron acceptor activities of wild-type and mutant NfsA and Frp

Electron acceptora	Reductase activity (μmol/min/mg of protein)
	Wild-type NfsAb	NfsA-97-99G	Frpc
Flavins
FMN	1	40	20
FAD	3	37	19
Riboflavin	7	44	18
Lumiflavin	10	54	16
Nitro compounds
Nitrofurazone	73	30	104
Methyl 4-nitrobenzoate	24	48	57
Quinones
Menadione	24	77	119
1,4-Benzoquinone	163	57	260
Miscellaneous
Tartrazine	0.8	27	0.1
Methylene blue	3	6	62
Ferricyanide	251	183	410
DCIP	27	7	98

^aFAD, flavin adenine dinucleotide; DCIP, 2,6-dichloroindophenol. 

^bZenno et al. (13). 

^cZenno et al. (12). Electron acceptor activities were measured at virtually saturating concentrations. Thus, the values shown here may correspond to the maximum velocities (V_max).