TABLE 1.

Reactions catalyzed by NfnAB from T. maritima

Reaction	Apparent Vmax at 45 °C	Apparent Km
	units/mg	mm
NADP+ reduction with
Fdred50%a + NADH	4.8	0.2 (NADP+)e
		0.02 (NADH)f
Fdred50%a	0.05
NADH	0.04
NADH + Fdoxb	0.04
Fdox reduction with
NADPHc + NAD+	3.9	0.002 (NADPH)g
		0.24 (NAD+)h
NADPHc	0.01
NAD+ reduction with
NADPHc + Fdoxb	2.2	0.001 (NADPH)i
		1.0 (NAD+)j
Fdred100%d	0.4
NADPHc + Fdred50%a	1.8
NADPHc + Fdred100%d	0.4
NADPHc	0.34

^a Fd_red50%-regenerating system (Fd, hydrogenase, and 100% H₂ keeping Fd about 50% reduced).

^b Fd_ox-regenerating system (Fd, hydrogenase, and 100% N₂ keeping Fd to almost 100% oxidized).

^c NADPH-regenerating system (NADP⁺, glucose-6-phosphate dehydrogenase, and glucose-6-phosphate keeping NADP to almost 100% reduced).

^d Fd_red100%-regenerating system (Fd, pyruvate, CoA, phosphotransacetylase, phosphate, thiamin pyrophosphate, pyruvate:ferredoxin oxidoreductase keeping Fd about 100% reduced).

^e 0.5 mm NADH, 25 μm Fd_red50%.

^f 2 mm NADP⁺, 25 μm Fd_red50%.

^g 10 mm NAD⁺, 31 μm Fd_ox.

^h 0.5 mm NADP⁺, 31 μm Fd_ox.

ⁱ 10 mm NAD⁺, 10 μm Fd_ox.

^j 10 mm NAD⁺, 10 μm Fd_ox.