TABLE 2.

Electron acceptor specificity of hydrogenasea

Electron acceptor (concn)Eo′ (mV)cRelative activity (%)
H. pyloriH. hepaticus
Methylene blue (200 μM)11100100
Phenazine methosulfate (400 μM)80>10089
DCPIPb (200 μM)2175468
Ferricyanide (1 mM)3608568
Cytochrome c (100 μM)2503371
Benzyl viologen (1 mM)−360<0.5<1.0
  • a The 100% activities (methylene blue rate) were 382 and 62 nmol/min/mg of protein for H. pylori (membranes) and H. hepaticus (permeabilized cells), respectively. The H. pylori data are from reference 12. The H. hepaticus permeabilized cells were prepared as described in footnote a of Table 1, and protein was measured with bicinchoninic acid (Pierce Chemical Co) after adding 1% sodium dodecyl sulfate and then heating cells (90°C for 10 min). All electron acceptor activities were determined at saturating levels anaerobically in the presence of 50 μM sodium dithionite.

  • b DCPIP, 2, 6-dichlorophenolindophenol.

  • c Eo′, standard oxidation-reduction potential.