Table 1. Biophysical characterization of purified [FeFe] hydrogenases produced in Escherichia coli.

	HydA1	CpI
H2 Uptake (MV) †	251±49	476±39
µmol H2·min−1·mg−1
H2 Evolution (MV) †	641±88	1087±146
µmol H2·min−1·mg−1
H2 Evolution (PetF) †	41±4	90±10
µmol H2·min−1·mg−1
Iron Content	4.5±0.2	13.2±1.3
Fe atoms·peptide−1
Purification Yield	30±11	7.9±0.8
mg·L−1 of culture

Data are the average from n = 3–6 cultures examined ± standard deviations.

^†Specific activities of purified hydrogenases were determined using methyl viologen (MV) or PetF ferredoxin as the electron donating or accepting substrates.