What is the function of hydrogenase?
Hydrogenases are key enzymes of the energy metabolism of many microorganisms. Especially in anoxic habitats where molecular hydrogen (H2) is an important intermediate, these enzymes are used to expel excess reducing power by reducing protons or they are used for the oxidation of H2 as energy and electron source.
What does hydrogenase mean?
A hydrogenase is an enzyme that catalyses the reversible oxidation of molecular hydrogen, as shown in below:++ Hydrogen uptake is coupled to the reduction of electron acceptors such as oxygen, nitrate, sulfate, carbon dioxide, and fumarate.
Is hydrogenase a protein?
The [NiFe] hydrogenases are heterodimeric proteins consisting of small (S) and large (L) subunits. The small subunit contains three iron-sulfur clusters while the large subunit contains the active site, a nickel-iron centre which is connected to the solvent by a molecular tunnel.
What is uptake hydrogenase?
The uptake hydrogenase is composed of small and large subunits, encoded by hupS and hupL, respectively. HupS mediates electron transport from the active site of the large subunit to redox partners and downstream reactions through a set of FeS clusters. HupL harbors the active site that contains the metals Ni and Fe.
Where is hydrogenase located?
Hydrogenases are mainly found in archaebacteria and bacteria, but occur in eukaryotic microorganisms as well. Depending on the type of metal ion present in their active center, they are subdivided into Ni-Fe-hydrogenases and single-Fe-hydrogenases, to which the subclass of free Fe-S hydrogenases also belongs.
What class of enzyme is a hydrogenase?
Hydrogenases are microbial enzymes which catalyze uptake and production of H2. Hydrogenases are classified into 10 classes based on the electron carrier specificity, or into 3 families, [NiFe]-family (including [NiFeSe]-subfamily), [FeFe]-family and [Fe]-family, based on the metal composition of the active site.
What is the role of hydrogenase in nitrogen fixation?
Hydrogenase recycles the H2 produced in N2 fixation, thereby minimizing the loss of energy during nitrogenase catalysis.
What is FeFe hydrogenase?
[FeFe]-Hydrogenases are the most efficient enzymes for catalytic hydrogen turnover. The incorporation of synthetically modified cofactors and utilization of semi-artificial enzymes only recently allowed us to shed light on key steps of the catalytic cycle.
Which algae is mostly used for hydrogen production?
Blue-green algae (cyanobacteria) are promising microorganisms for this. Advantages are hydrogen evolution is separated from oxygen evolution. It can also produce relatively higher hydrogen yields. Furthermore, by-products can be efficiently converted to hydrogen.
What microbes produce hydrogen?
The hydrogen-producing bacteria was dominated by the genera: Clostridium, Enterobacter, Klebsiella, Citrobacter, and Bacillus; the methanogens included the genera: Methanorix, Methanosarcina, Methanoculleus, Methanobrevibacter, Methanobacterium, Methanofollis, and Methanomassiliicoccus.
How is hydrogen made from algae?
Photosynthesis in cyanobacteria and green algae splits water into hydrogen ions and electrons. The electrons are transported over ferredoxins. Fe-Fe-hydrogenases (enzymes) combine them into hydrogen gas. Enclosing the microreactors with synergistic bacteria was shown to increase levels of hydrogen production.