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

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Abstract
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.