Carbon monoxide dehydrogenase

Several examples of electron transfer cofactors have been proposed, including Ferredoxin, NADP+/NADPH and flavoprotein complexes like flavin adenine dinucleotide (FAD) as well as hydrogenases.

[1][2][3][4] CODHs support the metabolisms of diverse prokaryotes, including methanogens, aerobic carboxidotrophs, acetogens, sulfate-reducers, and hydrogenogenic bacteria.

When acting in concert, either as structurally independent enzymes or in a bifunctional CODH/ACS unit, the two catalytic sites are key to carbon fixation in the reductive acetyl-CoA pathway.

Microbial organisms (Both aerobic and anaerobic) encode and synthesize CODH for the purpose of carbon fixation (CO oxidation and CO2 reduction).

Depending on attached accessory proteins (A,B,C,D-Clusters), serve a variety of catalytic functions, including reduction of [4Fe-4S] clusters and insertion of nickel.

An example for the latter case, Ni,Fe-CODHs form a bifunctional cluster with acetyl-CoA synthase, as has been well characterized in the anaerobic bacteria Moorella thermoacetica,[9][10] Clostridium autoethanogenum [11] and Carboxydothermus hydrogenoformans [12].

[21] The discovery of a functional CO tunnel places CODH on a growing list of enzymes that independently evolved this strategy to transfer reactive intermediates from one active site to another.

Two basic amino acids (Lys587 and His 113 in M.thermoacetica) reside in proximity to the C-cluster and facilitate acid-base chemistry required for enzyme activity.

Anaerobic micro-organisms like Acetogens use the Wood–Ljungdahl pathway, relying on CODH to reduce CO2 to CO, needed along with a methyl, coenzyme a (CoA) and corrinoid iron-sulfur protein for the synthesis of Acetyl-CoA.