Some characteristics of cytochrome c-555 isolated from sulfide oxidizing Xanthomonas sp. DY44

From a heterotrophic bacterium, Xanthomonas sp. DY44 which was previously reported to oxidize hydrogen sulfide (H₂S) to polysulfide, cytochrome c-555 (cyt. c-555) responsible for oxidation of sulfide was purified by DEAE-Toyopearl and Sepadex G-75 column chromatography. Cyt. c-555 with a molecular weight of 12,500 showed maximum absorption at 555 nm (α-peak), 522 nm (β-peak) and 417 nm (γ-peak) for the reduced form which was prepared by addition of Na₂S₂O₄. Cyt. c-555 was also reduced by addition of sulfide (Na₂S and H₂S), and the oxidized products of sulfide by cyt. c-555 was identified as polysulfide. The reduced form of cyt. c-555 was suggested to be oxidized coupled with cyt. c oxidase which is tolerant to sulfide.