The influence of [Fe]-hydrogenase from Clostridium acetobutylicum was studied on the anaerobic corrosion of mild steel. Two short-circuited mild steel electrodes were exposed to the same solution and hydrogenase was retained on the surface of only one electrode thanks to a dialysis membrane. The galvanic current and the electrode potential were measured as a function of time in order to monitor...

Recently Phelps and Wilson (1) reported the occurrence of hydrogenase, the enzyme which activates molecular hydrogen, in nitrogen-fixing bacteria. Because HZ specifically inhibits nitrogen fixation by red clover plants inoculated with Rhizobium trijolii as well as by Azotobacter (2,3), possession of hydrogenase by these organisms may be more than merely fortuitous. The possibility must be consi...

The nickel-dependent chemolithoautotrophic growth of Alcaligenes eutrophus is apparently due to a requirement of nickel for active hydrogenase formation. Cells grown heterotrophically with fructose and glycerol revealed a specific activity of soluble and membrane-bound hydrogenase which was severalfold higher than the normal autotrophic level. The omission of nickel from the medium did not affe...

When photosynthetic bacteria Rhodocyclus gelatinosus and Rhodospirillum rubrum were cultured with CO in the gas phase, a CO-linked pathway was quickly induced. These bacteria perform a water-gas shift reaction with CO and H2O, and produce H2 and CO2 in nearly stoichiometric quantities. The hydrogenase, a terminal enzyme of the linked pathway, is extremely O2 resistant. In order to further inves...

During anaerobic growth Escherichia coli synthesizes two membrane-associated hydrogen-oxidizing [NiFe]-hydrogenases, termed hydrogenase 1 and hydrogenase 2. Each enzyme comprises a catalytic subunit containing the [NiFe] cofactor, an electron-transferring small subunit with a particular complement of [Fe-S] (iron-sulfur) clusters and a membrane-anchor subunit. How the [Fe-S] clusters are delive...

[Fe]-hydrogenase is a newly characterized type of hydrogenase. This enzyme heterolytically splits hydrogen in the presence of a natural substrate. The active site of the enzyme contains a mono-iron complex with intriguing iron-acyl ligation. Several groups have recently developed iron-acyl complexes as synthetic models of [Fe]-hydrogenase. This Focus Review summarizes the studies of this enzyme...

BACKGROUND In symbiotic legume nodules, endosymbiotic rhizobia (bacteroids) fix atmospheric N(2), an ATP-dependent catalytic process yielding stoichiometric ammonium and hydrogen gas (H(2)). While in most legume nodules this H(2) is quantitatively evolved, which loss drains metabolic energy, certain bacteroid strains employ uptake hydrogenase activity and thus evolve little or no H(2). Rather, ...

This review provides a comprehensive overview of the synthesis, reactivity, and electrochemistry chemical models active site structures in [Fe] hydrogenase, an enzyme that catalyzes reversible reduction protons to submergence. Related literature on structure functions hydrogenase site, H cluster, is discussed with emphasis di-iron organosome. In addition, various methods for preparation charact...

Hydrogen-producing thermophilic cellulolytic microorganisms were isolated from cow faeces. Rates of cellulose hydrolysis and hydrogen formation were 0.2 mM L(-1) h(-1) and 1 mM L(-1) h(-1), respectively. An enzymatic fuel cell (EFC) with a hydrogenase anode was used to oxidise hydrogen produced in a microbial bioreactor. The hydrogenase electrode was exposed for 38 days (912 h) to a thermophili...

The physiological properties of a hyd mutant of Desulfovibrio vulgaris Hildenborough, lacking periplasmic Fe-only hydrogenase, have been compared with those of the wild-type strain. Fe-only hydrogenase is the main hydrogenase of D. vulgaris Hildenborough, which also has periplasmic NiFe- and NiFeSe-hydrogenases. The hyd mutant grew less well than the wild-type strain in media with sulfate as th...