Table 2.

Ethylene, hydrogen, and ammonia production activities of A. vinelandii and Roseiflexus Mo nitrogenases

	Substrate
	N2			Ar	C2H2
Product	NH3	H2	NH3/H2	H2	C2H4
NifDKAv	849 ± 58	716 ± 103	1.19	2,123 ± 233	1,835 ± 38
NifDKRS	149 ± 30	122 ± 32	1.22	443 ± 50	391 ± 55

Activities are nmol produced per min and mg of the corresponding NifDK. H₂ production was determined in Ar or N₂ atmospheres. Data are the average of n = 4 independent reactions (± SD). Values from negative control reactions lacking NifDK components were subtracted. A. vinelandii reactions were carried out at 30 °C by mixing NifDK^Av and NifH^Av in molar ratio of 1:40. Roseiflexus reactions were carried out at 48 °C by mixing apo-NifDK^RS and NifH^RS in molar ratio of 1:40, together with NifB^RS, RC-NifU^Av, molybdate, homocitrate, and SAM.