Azotobacter vinelandii cultures express more H2 uptake hydrogenase activity when fixing N2 than when provided with fixed N. Hydrogen, a product of the nitrogenase reaction, is at least partly responsible for this increase. The addition of H2 to NH4+-grown wild-type cultures caused increased whole-cell H2 uptake activity, methylene blue-dependent H2 uptake activity of membranes, and accumulation...

Rhodopseudomonas palustris is a purple, facultatively phototrophic bacterium that uses hydrogen gas as an electron donor for carbon dioxide fixation during photoautotrophic growth or for ammonia synthesis during nitrogen fixation. It also uses hydrogen as an electron supplement to enable the complete assimilation of oxidized carbon compounds, such as malate, into cell material during photoheter...

F(420)-nonreactive and F(420)-reactive hydrogenases have been partially purified from Methanococcus jannaschii, an extremely thermophilic methanogen isolated from a submarine hydrothermal vent. The molecular weights of both hydrogenases were determined by native gradient electrophoresis in 5 to 27% polyacrylamide gels. The F(420)-nonreactive hydrogenase produced one major band (475 kilodaltons)...

Membrane-associated hydrogenase was purified from the chemolithoautotrophic epsilonproteobacterium Hydrogenimonas thermophila at 152-fold purity. The hydrogenase was found to be localized in the periplasmic space, and was easily solubilized with 0.1% Triton X-100 treatment. Hydrogen oxidation activity was 1,365 micromol H(2)/min/mg of protein at 80 degrees C at pH 9.0, with phenazine methosulph...

Acetylene is a slow-binding inhibitor of the Ni- and Fe-containing dimeric hydrogenase isolated from Azotobacter vinelandii. Acetylene was released from hydrogenase during the recovery from inhibition. This indicates that no transformation of acetylene to another compound occurred as a result of the interaction with hydrogenase. However, the release of C2H2 proceeds more rapidly than the recove...

The nickel-containing enzymes of Helicobacter pylori, urease and hydrogenase, are essential for efficient colonization in the human stomach. The insertion of nickel into urease and hydrogenase is mediated by the accessory protein HypA. HypA contains an N-terminal nickel-binding site and a dynamic structural zinc-binding site. The coordination of nickel and zinc within HypA is known to be critic...

Nitrogenase, [FeFe]-hydrogenase, and [Fe]-hydrogenase enzymes perform catalysis at metal cofactors with biologically unusual non-protein ligands. The FeMo cofactor of nitrogenase has a MoFe7S9 cluster with a central carbon, whereas the H-cluster of [FeFe]-hydrogenase contains a 2Fe subcluster coordinated by cyanide and CO ligands as well as dithiomethylamine; the [Fe]-hydrogenase cofactor has C...

Hydrogenase (hydrogen:ferricytochrome c(3) oxidoreductase, EC 1.12.2.1) from Desulfovibrio vulgaris was encapsulated in reversed micelles with cetyltrimethylammonium bromide as surfactant and a chloroform/octane mixture as solvent. Reducing equivalents for hydrogenase-catalyzed hydrogen production were provided by vectorial photosensitized electron transfer from a donor (thiophenol) in the orga...

The cyanobacterium Synechocystis sp. PCC 6803 has a bidirectional [NiFe]-hydrogenase (Hox hydrogenase) which reversibly reduces protons to H2. This enzyme is composed of a hydrogenase domain and a diaphorase moiety, which is distinctly homologous to the NADH input module of mitochondrial respiratory Complex I. Hox hydrogenase physiological function is still unclear, since it is not required for...

Uptake hydrogenase is an enzyme that is beneficial for nitrogen fixation in bacteria. Recent studies have shown that Frankia sp. has two sets of uptake hydrogenase genes, organized in synton 1 and synton 2. In the present study, phylogenetic analysis of the structural subunits of hydrogenase syntons 1 and 2 showed a distinct clustering pattern between the proteins of Frankia strains that were i...