Purification and characterization of sulfide dehydrogenase from alkaliphilic chemolithoautotrophic sulfur-oxidizing bacteria

Extracts of the alkaliphilic sulfur-oxidizing autotroph strain AL3 contained sulfide:cytochrome c oxidoreductase. This was active above pH 8, and was associated with the cell membranes. Although up to 60% of the initial activity was lost during Triton X-100 extraction, further purification resulted in an enzyme that catalyzed sulfide oxidation with horse heart cytochrome c. This enzyme was a 41 kDa protein containing heme c(554). The optimum pH of the membrane bound enzyme was 9.0, but after extraction this fell to 8.0, The enzyme catalyzed a single electron oxidation of HS-. Hydrosulfide radical is therefore the most probable product. (C) 1998 Federation of European Biochemical Societies.