FIG. 4.

UV-visible spectra of the selected CooA homologs. (A) R. rubrum CooA; (B) C. hydrogenoformans 2340 CooA; (C) C80S C. hydrogenoformans 2340 CooA; (D) A. vinelandii CooA. CooA proteins were partially purified from anaerobically grown cells by the hydroxylapatite preparation described in Materials and Methods. Analyzed samples were diluted to 1 mg of protein/ml. For the spectra of C. hydrogenoformans 2340 CooA proteins, 20 μM potassium ferricyanide [K₃Fe(CN)₆] was added to the as isolated forms of the proteins.