Carbon monoxide dehydrogenase acetogenic bacteria

Nickel is found in at least four enzymes urease, certain hydrogenases, methyl-CoM reductase (in its cofactor F430) of methanogenic bacteria, and carbon monoxide dehydrogenase of acetogenic and methanogenic bacteria 434... 

Nickel in Carbon Monoxide Dehydrogenase from Acetogenic Bacteria 645... 

This is a noncyclic pathway that also results in the fixation of two molecules of C02 to form acetyl-CoA. It was elucidated by Wood, Ljungdahl, Thauer and others as a pathway which is used by acetogenic bacteria to synthesize acetate from C02 in their energy metabolism [21]. The acetyl-CoA pathway resembles the Monsanto process of acetate synthesis from CO and methanol, with one molecule of C02 being reduced to the level of methyltetrahydropterin, while another C02 molecule is reduced to the level of carbon monoxide in the reaction catalyzed by the nickel-dependent carbon monoxide dehydrogenase (Figure 3.3). 

Ragsdale, S. W., and Wood, H. G., 1985, Acetate biosynthesis by acetogenic bacteria evidence that carbon monoxide dehydrogenase is the condensing enzyme that catalyzes the final steps of the synthesis, J. Biol. Chem. 260 397093977. 

Carbon monoxide dehydrogenase has been isolated from several acetogenic bacteria and purified in some cases, as shown in Table 20. This also contains details of carbon monoxide dehydrogenases from methanogens. The enzymes from C. thermoaceticum and A woodii have been compared. They both have molecular weights about 450 000 with six subunits, (0)8)3, but can exist as dimers, 0)3. The larger subunits appear to be identical in both cases, but the smaller ones differ. Nickel is present in concentrations that suggest two Ni per molecule of dimeric enzyme. There also appear to be two or three [4Fe-4S] clusters per dimeric enzyme, while the A. woodii enzyme may have a 3Fe centre. 

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