Table 3.

Activation of ΔnifB MoFe protein by FeMoco and precursor

		Product (nmol/mg protein/min)a
Cluster	Substrate	NH3	H2	C2H4
FeMoco	C2H2/Arb	-	84±5 (83)	1187±18 (96)
	H+/Ar	-	1362±57 (88)	-
	N2	618±52 (92)	254±17 (98)	-
Precursor	C2H2/Arb	-	371±29 (9)	119±6 (10)
	H+/Ar	-	474±22 (6)	-
	N2	0 (N/A)c	459±36 (5)	-

^aPercentages of activities retained after subjecting the samples to the gel filtration chromatography are given in parentheses.

^bMaximum activity was observed at 10% and 60% C₂H₂, respectively, for the activation of ΔnifB MoFe protein by FeMoco and precursor.

^cN/A = not applicable