Carbon dioxide activation at the Ni,Fe-cluster of anaerobic carbon monoxide dehydrogenase.
Jeoung, J.H., Dobbek, H.(2007) Science 318: 1461-1464
- PubMed: 18048691 
- DOI: https://doi.org/10.1126/science.1148481
- Primary Citation of Related Structures:  
3B51, 3B52, 3B53 - PubMed Abstract: 
Anaerobic CO dehydrogenases catalyze the reversible oxidation of CO to CO2 at a complex Ni-, Fe-, and S-containing metal center called cluster C. We report crystal structures of CO dehydrogenase II from Carboxydothermus hydrogenoformans in three different states. In a reduced state, exogenous CO2 supplied in solution is bound and reductively activated by cluster C. In the intermediate structure, CO2 acts as a bridging ligand between Ni and the asymmetrically coordinated Fe, where it completes the square-planar coordination of the Ni ion. It replaces a water/hydroxo ligand bound to the Fe ion in the other two states. The structures define the mechanism of CO oxidation and CO2 reduction at the Ni-Fe site of cluster C.
Organizational Affiliation: 
Laboratorium Proteinkristallographie and Forschungszentrum für Bio-Makromoleküle, Universität Bayreuth, D-95440 Bayreuth, Germany.