FIG. 3.

Cells containing most CooA homologs accumulate heme-containing proteins. CooA proteins were partially purified from anaerobically grown cells by the hydroxylapatite preparation described in Materials and Methods. The spectrum of each partially purified sample was corrected by subtracting the spectrum of a similarly treated control sample of the same protein concentration prepared from a strain containing only the pEXT20 vector. OD, optical density.