Purification and Some Properties of a Hydrogen Sulfide-binding Protein That Is Involved in Sulfur Oxidation ofThiobacillus ferrooxidans

Abstract

A hydrogen sulfide: ferric ion oxidoreductase (SFORase), which is crucial in sulfur oxidation of T. ferrooxidans AP19-3, oxidizes hydrogen sulfide with Fe 3 + as an electron acceptor to give sulfite ion and Fe 2 +. When washed intact cells of T. ferrooxidans AP19-3 were treated with hydrogen sulfide solution (100 mM) at pH 6.5 for 1 hr, a heat stable reduced sulfur containing protein, which serves as a reduced sulfur compound for purified SFORase to give sulfite, was formed in the plasma membrane of this strain. The protein, which can bind hydrogen sulfide reversibly, was solubilized from plasma membrane with 1% SDS and purified to an electrophoretically homogeneous state. We tentatively named the protein hydrogen sulfide-binding protein (SBP). SBP had an apparent molecular weight of 16,000 in the presence of 1% SDS. One molecule of SBP had 4.5 molecules of iron and could bind 2.3 molecules of hydrogen sulfide.· The hydrogen sulfide bound to SBP was oxidized by a purified SFORase to give sulfite ion, suggesting that SBP is involved in sulfur oxidation of this bacterium.

Distinct Physiological Roles of the Three [NiFe]-Hydrogenase Orthologs in the Hyperthermophilic Archaeon Thermococcus kodakarensis

“…The amount of H 2 was quantified by gas chromatography (GC-14A; Shimadzu, Kyoto, Japan) with a thermal conductivity detector. The amount of H 2 S was quantified by the methylene blue method as described elsewhere (45). The amounts of gas metabolites generated were normalized by cell mass, which was determined by measuring the turbidity of the culture broth.…”

Involvement of Sulfide:Quinone Oxidoreductase in Sulfur Oxidation of an Acidophilic Iron-Oxidizing Bacterium,Acidithiobacillus ferrooxidansNASF-1

“…43) A hydrogen sulfide-binding protein, which reversibly bound hydrogen sulfide, has been purified from the membrane fraction of A. ferrooxidans AP19-3. 44) Banco and Ingledew also found that A. ferrooxidans released a small amount of hydrogen sulfide during aerobic and anaerobic incubation with elemental sulfur, suggesting that the activation step in sulfur oxidation might involve an initial reductive step of elemental sulfur. 45) Although the enzymatic mechanism for the production of hydrogen sulfide under aerobic conditions is still unclear, hydrogen sulfide does occur in A. ferrooxidans cells.…”

Thiosulfate Reductase from a Moderately Thermophilic Iron-oxidizing Bacterium, Strain TI-1—Purification and Characterization

“…Hydrogen sulfide was measured by the methylene blue method. 19) The reaction mixture contained 400 p,l of 0.1 M sodium citrate buffer (pH 6.0), 50 p,l of 10 mM NAD H, 100 p,l of 10 mM sodium thiosulfate, and enzyffii~ solution. Total volume was 600 p,l.…”

“…After incubating the reac-tion mixture at 4SoC for S min, the reaction was started by adding sodium thiosulfate and stopped by adding 200 {ll of 2 M NaOH. Deionized water (800 {ll) and diamine-ferric chloridle solution (400 {ll) 19) were added to the solution. The blue color resulting from the production of methylene blue was measured by a Shimadzu UV-1200 spectrophotometer at 670nm.…”