Carbon monoxide dehydrogenase activity

Carbon monoxide dehydrogenase active site CO oxidation / CO, reduction... 

Xia J, Hu Z, Popescu CV, et al. 1997. Mossbauer and EPR study of the Ni-activated a-subunit of carbon monoxide dehydrogenase from Clostridium thermoaceticum. J Am Chem Soc 119 8301-12. 

Smith MC, Barclay JE, Cramer SP, Davies SC, Gu W-W, Hughes DL, Longhurst S, Evans DJ (2002) Nickel-iron-sulfur complexes approaching structural analogues of the active sites of NiFe-hydrogenase and carbon monoxide dehydrogenase/acetyl-CoA synthase. Dalton Trans. 2641-2647... 

There are now three different proteins of the XDH/XO family whose structures have been determined by X-ray protein crystallography. The structure of aldehyde oxidoreductase from the bacterium Desulfovibrio gigas was the first X-ray structure determined for an oxo-molybdenum enzyme (17) and has been followed by stmctures of XO/XDH (10) and carbon monoxide dehydrogenase (CODH) (19, 21). Although the three enzymes are placed in the same family, there are structural differences among them at the active site and at the phosphate remote from the Mo center. 

The C-cluster of carbon monoxide dehydrogenase is the active site for the oxidation of CO to CO 2. This conclusion is based on rapid kinetic studies in which changes in the spectra of Cluster C undergo changes at rates commensurate with the rate of CO oxidation (Kumar et al., 1993). In addition, cyanide, which is a relatively specific inhibitor of CO oxidation, binds specifically to Cluster C (Anderson et al., 1993). 

Russell, W. K., Stalhmidske, C. M. V., Xia, J. Q., Scott, R. A., and Lindahl, P. A., 1998, Spech o-scopic, redox, and structural characterization of die Ni-labile and nonlabile forms of the acetyl-CoA synthase active. Site of carbon monoxide dehydrogenase, J. Am. Chem. Soc. 120(30) 7502n7510. 

The active site of carbon monoxide dehydrogenase has been shown to contain an asymmetric [Ni-4Fe-5S] cluster. There have been two recent independent reports of X-ray stmctures for the biftmctional enzyme carbon monoxide dehydrogenase/acetyl-coenzyme A synthase. In both stmctures, Ni is also bound in the acetyl-coenzyme A synthase within a N2S2 environment originating from amide N- and thiolate S-donors. The latter donors bridge to either a Cu, Zn, or Ni, which in turn is coimected to a 4Fe4S cluster. ... 

Since 1975 four classes of nickel metalloenzymes have been identified (77). The nickel hydrogenases and carbon monoxide dehydrogenases are considered here and the dinuclear active site of urease is described in Section IVB. The fourth class, methyl-S-coenzyme-M reductases,... 

Nickel is an essential element in small amounts, is a component of the important enzymes urease, carbon monoxide dehydrogenase, hydrogenase and methyl-S-coenzyme M reductase, and lies at their active sites. Nickel can exist under physiological conditions in oxidation states I, II and III, but the higher two seem most relevant. 

The bifunctional carbon monoxide dehydrogenase (CODH)/acetyl-CoA synthase enzyme is a key enzyme involved in the Wood-Ljungdahl pathway of carbon fixation that operates in anaerobic bacteria. As such, it is a major player in the global carbon cycle. The CODH component of the enzyme catalyzes the reversible reduction of CO2 to CO (Equation (15)), which is then channeled to the ACS active site where it reacts with CoA and a methyl group provided by the corrinoid iron-sulfur protein (CFeSP) to form acetyl-CoA 30 (Equation (16)). 

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