PURIFICATION AND CHARACTERIZATION OF SULFIDE DEHYDROGENASE FROM ALKALIPHILIC CHEMOLITHOAUTOTROPHIC SULFUR-OXIDIZING BACTERIA

Extracts of the alkaliphilic sulfur-oxidizing autotroph strain AL3 con tained sulfide:cytochrome c oxidoreductase. This was active above pH 8 , and was associated with the cell membranes. Although up to 60% of th e initial activity was lost during Triton X-100 extraction, further pu rification 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 elec tron oxidation of HS-. Hydrosulfide radical is therefore the most prob able product. (C) 1998 Federation of European Biochemical Societies.