"Cluster B is an all-cysteinyl-liganded 4Fe-4S cluster; cluster C is a mixed Ni-Fe-S cluster which is the active site of CO oxidation. Cluster D is also an all-cysteinyl-liganded 4Fe-4S cluster that bridges the two subunits of the CODH dimer. Contains two additional 4Fe-4S clusters, dubbed E and F, that probably transport electrons from ferredoxin to the B cluster."xsd:string