Purification and characterization of sulfur reductase from a moderately thermophilic bacterial strain, TI-1, that oxidizes iron.
A moderately thermophilic bacterium, strain TI-1, produces H2S outside of the cells when grown at 45 degrees C on Fe(2+)-medium (pH 1.8) containing elemental sulfur and L-glutamic acid. A newly identified sulfur reductase was present in the cytosol of this strain and was purified to an electrophoretically homogeneous state from strain TI-1. The apparent molecular weight of sulfur reductase was 86,000 by gel filtration and 48,000 by SDS-PAGE, so the enzyme was a homodimer. The enzyme was most active at pH 9.0 and 60 to 70 degrees C, and it catalyzed the reduction of 1 mol of elemental sulfur with 1 mol of NADH to give 1 mol of H2S and 1 mol of NAD+. Elemental sulfur was a specific electron acceptor of this enzyme. Thiosulfate, sulfite, and tetrathionate were not electron acceptors, but inhibited sulfur reductase activity. NADPH was not used as an electron donor.
Sugio
T
T
Division of Biological Function and Genetic Resources Science, Faculty of Agriculture, Okayama University, Japan.
Oda
K
K
Matsumoto
K
K
Takai
M
M
Wakasa
S
S
Kamimura
K
K
D000135:Acid Phosphatase / Q000378:metabolism; D001419:Bacteria / Q000201:enzymology*; D001426:Bacterial Proteins / Q000302:isolation & purification; D002614:Chelating Agents / Q000494:pharmacology; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D006862:Hydrogen Sulfide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism*; D008970:Molecular Weight; D009997:Osmotic Pressure; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry* / Q000302:isolation & purification; D013379:Substrate Specificity; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D013696:Temperature
D001426:Bacterial Proteins; D002614:Chelating Agents; D013439:Sulfhydryl Reagents; D007501:Iron; D010088:Oxidoreductases; D005954:Glucosephosphate Dehydrogenase; C074883:polysulfide reductase; D000135:Acid Phosphatase; D006862:Hydrogen Sulfide