This enzyme, which is found in thermophilic microorganisms, contains one mononuclear none-heme iron centre per subunit. Elemental sulfur is both the electron donor and one of the two known acceptors, the other being oxygen. Thiosulfate is also observed as a product, but is likely formed non-enzymically by a reaction between sulfite and sulfur . This enzyme differs from EC 1.13.11.18, sulfur dioxygenase and EC 1.12.98.4, sulfhydrogenase, in that both activities occur simultaneously.
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SYSTEMATIC NAME
IUBMB Comments
sulfur:oxygen oxidoreductase (hydrogen-sulfide- and sulfite-forming)
This enzyme, which is found in thermophilic microorganisms, contains one mononuclear none-heme iron centre per subunit. Elemental sulfur is both the electron donor and one of the two known acceptors, the other being oxygen. Thiosulfate is also observed as a product, but is likely formed non-enzymically by a reaction between sulfite and sulfur [1]. This enzyme differs from EC 1.13.11.18, sulfur dioxygenase and EC 1.12.98.4, sulfhydrogenase, in that both activities occur simultaneously.
in the presence of oxygen but not under a hydrogen atmosphere, the enzyme simultaneously produces sulfite, thiosulfate, and hydrogen sulfide from sulfur. Nonenzymatic control experiments show that thiosulfate is produced mainly in a chemical reaction between sulfite and sulfur. The ratio of sulfite to hydrogen sulfide production is 5:4 in the presence of zinc ions
iron content: 0.45 mol per mol subunit for recombinant wild-type enzyme, below 0.1 mol per mol subunit for mutant enzyme H86A, below 0.02 mol per mol subunit for mutant enzyme H90A, below 0.01 mol per mol subunit for mutant enzyme E114A, 0.02 mol per mol subunit for mutant enzyme E114D, 0.47 mol per mol subunit for mutant enzyme C31A, 0.42 mol per mol subunit for mutant enzyme C31S, 0.22 mol per mol subunit for mutant enzyme C101A, below 0.03 mol per mol subunit for mutant enzyme C101S, 0.19 mol per mol subunit for mutant enzyme C104A, 0.3 mol per mol subunit for mutant enzyme C104S, 0.56 mol per mol subunit for mutant enzyme C101A/C104A, 0.4 mol per mol subunit for mutant enzyme C101S/C104S
non-heme iron. The iron site and the three conserved cysteine residues are located in an active site pocket that is connected to the inner cavity of the sphere by a narrow pore formed by two adjacent methionines and a phenylalanine
low-potential mononuclear non-heme iron site ligated by a 2-His-1-carboxylate facial triad in a pocket of each subunit constitutes the active sites, accessible from the inside of the sphere. The iron is likely the site of both sulfur oxidation and sulfur reduction
0.5 mM, 95% inhibition of oxygenase reaction (formation of hydrogen sulfide), 84% inhibition of reductase reaction (formation of sulfite plus thiosulfate)
zinc binds far from the actIve sIte , Zn2+ interferes over a distance with the subunit pores in the outer shell, possibly by restriction of protein flexibility or substrate access or product exit
opening the putative substrate and product pathways in the outer shell leads to a significant increase in specific activity and to a shift in the stoichiometry of the products
opening the putative substrate and product pathways in the outer shell leads to a significant increase in specific activity and to a shift in the stoichiometry of the products
sulfur oxygenase reductase is the initial enzyme of the sulfur oxidation pathway in the thermoacidophilic Archaeon Acidianus ambivalens catalyzing an oxygen-dependent sulfur disproportionation to H2S, sulfite and thiosulfate
the spherical, hollow, cytoplasmic enzyme is composed of 24 identical subunits with an active site pocket each comprising a mononuclear non-heme iron site and a cysteine persulfide. Substrate access and product exit occur via apolar chimney-like protrusions at the fourfold symmetry axes, via narrow polar pores at the threefold symmetry axes and via narrow apolar pores within in each subunit. The expansion of the pores in the outer shell leads to an increased enzyme activity while the integrity of the active site pore seems to be important. The iron site and the three conserved cysteine residues are located in an active site pocket that is connected to the inner cavity of the sphere by a narrow pore formed by two adjacent methionines and a phenylalanine. Modeling of the SOR and its pores, overview. Opening the putative substrate and product pathways in the outer shell leads to a significant increase in specific activity and to a shift in the stoichiometry of the products
the spherical, hollow, cytoplasmic enzyme is composed of 24 identical subunits with an active site pocket each comprising a mononuclear non-heme iron site and a cysteine persulfide. Substrate access and product exit occur via apolar chimney-like protrusions at the fourfold symmetry axes, via narrow polar pores at the threefold symmetry axes and via narrow apolar pores within in each subunit. The expansion of the pores in the outer shell leads to an increased enzyme activity while the integrity of the active site pore seems to be important. The iron site and the three conserved cysteine residues are located in an active site pocket that is connected to the inner cavity of the sphere by a narrow pore formed by two adjacent methionines and a phenylalanine. Modeling of the SOR and its pores, overview. Opening the putative substrate and product pathways in the outer shell leads to a significant increase in specific activity and to a shift in the stoichiometry of the products
24 * 36000, ball-shaped assembly with a central hollow core probably consisting of 24 subunits in a 432 symmetry, the subunits form homodimers as the building blocks of the holoenzyme, SDS-PAGE
24 * 36000, ball-shaped assembly with a central hollow core probably consisting of 24 subunits in a 432 symmetry, the subunits form homodimers as the building blocks of the holoenzyme, SDS-PAGE
X-ray crystallography of SOR wild-type crystals soaked with inhibitors Hg2+ and iodoacetamide, X-ray diffraction structure determination and analysis at 1.7-2.5 A resolution, crystal structure analysis
iron content is 49% of that of the recombinant wild-type enzyme, oxygenase activity is 12.8% of the activity of recombinant wild-type enzyme, reductase activity is 10.3% of the activity of recombinant wild-type enzyme
iron content is 124% of that of the recombinant wild-type enzyme, oxygenase activity is 9.7% of the activity of recombinant wild-type enzyme, reductase activity is 15.3% of the activity of recombinant wild-type enzyme
mutant enzyme contains no iron, oxygenase activity is 1.04% of the activity of recombinant wild-type enzyme, reductase activity is 0.5% of the activity of recombinant wild-type enzyme
iron content is 89% of that of the recombinant wild-type enzyme, oxygenase activity is 19.8% of the activity of recombinant wild-type enzyme, reductase activity is 27.9% of the activity of recombinant wild-type enzyme
iron content is 42% of that of the recombinant wild-type enzyme, oxygenase activity is 11.8% of the activity of recombinant wild-type enzyme, reductase activity is 5.5% of the activity of recombinant wild-type enzyme
iron content is 67% of that of the recombinant wild-type enzyme, oxygenase activity is 19.8% of the activity of recombinant wild-type enzyme, reductase activity is 14.3% of the activity of recombinant wild-type enzyme
iron content is 4.4% of wild-type value, sulfur-oxidizing and sulfur-reducing activity is about 1% of the activity of activity of the recombinant wild-type enzyme
expression in Escherichia coli results in active, soluble SOR and in inclusion bodies from which active SOR can be refolded as long as ferric ions are present in the refolding solution. Wild-type, recombinant and refolded enzyme possesses indistinguishable properties
the sor gene, including codons for a C-terminally fused Strep tag, is cloned under the control of the tf55alpha promoter. Single transformants of Sulfolobus solfataricus PH1-16 containing the pMJ05-sor construct are grown at 78°C and subsequently shifted to 88°C to induce the expression of the sor gene
Coupled enzymatic production of sulfite, thiosulfate, and hydrogen sulfide from sulfur: purification and properties of a sulfur oxygenase reductase from the facultatively anaerobic archaebacterium Desulfurolobus ambivalens
Sulfur oxidation and reduction in Archaea: Sulfur oxygenase/-reductase and hydrogenases from the extremely thermophilic and facultatively anaerobic archaeon Desulfurolobus ambivalens