Purification and characterization of two new c‐type cytochromes involved in Fe2+ oxidation from Thiobacillus ferrooxidans

Two new c‐type cytochromes have been purified from cell membranes of the acidophilic Thiobacillus ferrooxidans. In contrast to a soluble cytochrome c with molecular mass of 14 kDa reported earlier, a membrane‐bound cytochrome c with a mass of 21 kDa was solubilized with octylthioglucoside and purified to homogeneity. In addition, a high molecular mass c‐type cytochrome (68 kDa) was also solubilized and purified using Triton X‐100 as a detergent. Both acid‐stable species are partially released during osmotic shock and chloroform treatment of the bacteria; they are integral components in the respiratory chain donating electrons to the terminal cytochrome oxidase.