Enzymes
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- Name help_outline H2O Identifier CHEBI:15377 (Beilstein: 3587155; CAS: 7732-18-5) help_outline Charge 0 Formula H2O InChIKeyhelp_outline XLYOFNOQVPJJNP-UHFFFAOYSA-N SMILEShelp_outline [H]O[H] 2D coordinates Mol file for the small molecule Search links Involved in 6,048 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline O2 Identifier CHEBI:15379 (CAS: 7782-44-7) help_outline Charge 0 Formula O2 InChIKeyhelp_outline MYMOFIZGZYHOMD-UHFFFAOYSA-N SMILEShelp_outline O=O 2D coordinates Mol file for the small molecule Search links Involved in 2,648 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline sulfur Identifier CHEBI:26833 (CAS: 7704-34-9) help_outline Charge 0 Formula S InChIKeyhelp_outline NINIDFKCEFEMDL-UHFFFAOYSA-N SMILEShelp_outline [S] 2D coordinates Mol file for the small molecule Search links Involved in 17 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H+ Identifier CHEBI:15378 Charge 1 Formula H InChIKeyhelp_outline GPRLSGONYQIRFK-UHFFFAOYSA-N SMILEShelp_outline [H+] 2D coordinates Mol file for the small molecule Search links Involved in 9,176 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline hydrogen sulfide Identifier CHEBI:29919 (CAS: 15035-72-0) help_outline Charge -1 Formula HS InChIKeyhelp_outline RWSOTUBLDIXVET-UHFFFAOYSA-M SMILEShelp_outline [S-][H] 2D coordinates Mol file for the small molecule Search links Involved in 54 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline sulfite Identifier CHEBI:17359 (CAS: 14265-45-3) help_outline Charge -2 Formula O3S InChIKeyhelp_outline LSNNMFCWUKXFEE-UHFFFAOYSA-L SMILEShelp_outline [O-]S([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 55 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
RHEA:13957 | RHEA:13958 | RHEA:13959 | RHEA:13960 | |
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Publications
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X-ray structure of a self-compartmentalizing sulfur cycle metalloenzyme.
Urich T., Gomes C.M., Kletzin A., Frazao C.
Numerous microorganisms oxidize sulfur for energy conservation and contribute to the global biogeochemical sulfur cycle. We have determined the 1.7 angstrom-resolution structure of the sulfur oxygenase reductase from the thermoacidophilic archaeon Acidianus ambivalens, which catalyzes an oxygen-de ... >> More
Numerous microorganisms oxidize sulfur for energy conservation and contribute to the global biogeochemical sulfur cycle. We have determined the 1.7 angstrom-resolution structure of the sulfur oxygenase reductase from the thermoacidophilic archaeon Acidianus ambivalens, which catalyzes an oxygen-dependent disproportionation of elemental sulfur. Twenty-four monomers form a large hollow sphere enclosing a positively charged nanocompartment. Apolar channels provide access for linear sulfur species. A cysteine persulfide and a low-potential mononuclear non-heme iron site ligated by a 2-His-1-carboxylate facial triad in a pocket of each subunit constitute the active sites, accessible from the inside of the sphere. The iron is likely the site of both sulfur oxidation and sulfur reduction. << Less
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Molecular characterization of the sor gene, which encodes the sulfur oxygenase/reductase of the thermoacidophilic Archaeum Desulfurolobus ambivalens.
Kletzin A.
A 5.8-kbp HindIII fragment containing the sor gene which encodes the aerobically induced sulfur oxygenase/reductase of the thermoacidophilic, chemolithoautotrophic, and facultatively anaerobic archaeum Desulfurolobus ambivalens, was cloned in pUC18 by using an oligonucleotide derived from the N-te ... >> More
A 5.8-kbp HindIII fragment containing the sor gene which encodes the aerobically induced sulfur oxygenase/reductase of the thermoacidophilic, chemolithoautotrophic, and facultatively anaerobic archaeum Desulfurolobus ambivalens, was cloned in pUC18 by using an oligonucleotide derived from the N-terminal amino acid sequence for identification (pSOR-1/17). The native enzyme is a 550,000-molecular-weight oligomer composed of single 40,000-molecular-weight subunits; this oligomer is capable of the simultaneous oxidation and reduction of sulfur (A. Kletzin, J. Bacteriol. 171:1638-1643, 1989). From the fragment, 3,025 bp that contained the entire sor gene were sequenced. The sor gene encoded a protein with 309 amino acid residues (molecular weight, 35,317). The transcript length was determined by Northern RNA hybridization to be 960 to 1,020 nucleotides, and the transcriptional start site was mapped by primer extension analysis. The transcript of the sor gene in aerobically grown cells was amplified 38-to 42-fold relative to that in anaerobically grown cells. An initial transcriptional characterization of three neighboring genes of unknown function is also reported. << Less
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Purification and properties of the sulfur oxygenase/reductase from the acidothermophilic archaeon, Acidianus strain S5.
Sun C.W., Chen Z.W., He Z.G., Zhou P.J., Liu S.J.
The sulfur oxygenase/reductase (SOR) of Acidianus strain S5 was purified and characterized after expressing the SOR gene in a recombinant strain of Escherichia coli. The N-terminal sequence of the purified SOR protein was the same as the deduced amino acid sequence from previously cloned SOR genes ... >> More
The sulfur oxygenase/reductase (SOR) of Acidianus strain S5 was purified and characterized after expressing the SOR gene in a recombinant strain of Escherichia coli. The N-terminal sequence of the purified SOR protein was the same as the deduced amino acid sequence from previously cloned SOR genes. Enzymatic studies indicated that the SOR catalyzed the conversion of elemental sulfur (S(o)) to sulfite, thiosulfate, and sulfide. The optimal pH and temperature were 5.0 and 70 degrees C, respectively. Comparison of this SOR and that of A. ambivalens revealed several differences between these two SORs. The most striking difference is that the SOR of Acidianus S5 had maximal activity at acidic pH. By application of anti-SOR serum and the Western blot technique, it was found that SOR proteins existed in A. brierleyi and in Acidianus S5 cells cultivated with thiosulfate as the sole energy source, indicating that SOR may also play a role in thiosulfate metabolism. << Less
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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.
Kletzin A.
From aerobically grown cells of the extremely thermophilic, facultatively anaerobic chemolithoautotrophic archaebacterium Desulfurolobus ambivalens (DSM 3772), a soluble oxygenase reductase (SOR) was purified which was not detectable in anaerobically grown cells. In the presence of oxygen but not ... >> More
From aerobically grown cells of the extremely thermophilic, facultatively anaerobic chemolithoautotrophic archaebacterium Desulfurolobus ambivalens (DSM 3772), a soluble oxygenase reductase (SOR) was purified which was not detectable in anaerobically grown cells. In the presence of oxygen but not under a hydrogen atmosphere, the enzyme simultaneously produced sulfite, thiosulfate, and hydrogen sulfide from sulfur. Nonenzymatic control experiments showed that thiosulfate was produced mainly in a chemical reaction between sulfite and sulfur. The maximum specific activity of the purified SOR in sulfite production was 10.6 mumol/mg of protein at pH 7.4 and 85 degrees C. The ratio of sulfite to hydrogen sulfide production was 5:4 in the presence of zinc ions. The temperature range of enzyme activity was 50 to 108 degrees C, with a maximum at 85 degrees C. The molecular mass of the native SOR was 550 kilodaltons, determined by gel filtration. It consisted of identical subunits with an apparent molecular mass of 40 kilodaltons in sodium dodecyl sulfate-gel electrophoresis. The particle diameter in electron micrographs was 15 /+-1.5 nm. The enzyme activity was inhibited by the thiol-binding reagents p-chloromercuribenzoic acid, N-ethyl maleimide, and 2-iodoacetic acid and by flavin adenine dinucleotide, Fe3+, and Fe2+. It was not affected by CN-, N3-, or reduced glutathione. << Less
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The sulphur oxygenase reductase from Acidianus ambivalens is a multimeric protein containing a low-potential mononuclear non-haem iron centre.
Urich T., Bandeiras T.M., Leal S.S., Rachel R., Albrecht T., Zimmermann P., Scholz C., Teixeira M., Gomes C.M., Kletzin A.
The SOR (sulphur oxygenase reductase) is the initial enzyme in the sulphur-oxidation pathway of Acidianus ambivalens. Expression of the sor gene in Escherichia coli resulted in active, soluble SOR and in inclusion bodies from which active SOR could be refolded as long as ferric ions were present i ... >> More
The SOR (sulphur oxygenase reductase) is the initial enzyme in the sulphur-oxidation pathway of Acidianus ambivalens. Expression of the sor gene in Escherichia coli resulted in active, soluble SOR and in inclusion bodies from which active SOR could be refolded as long as ferric ions were present in the refolding solution. Wild-type, recombinant and refolded SOR possessed indistinguishable properties. Conformational stability studies showed that the apparent unfolding free energy in water is approx. 5 kcal x mol(-1) (1 kcal=4.184 kJ), at pH 7. The analysis of the quaternary structures showed a 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. Iron was found in the wild-type enzyme at a stoichiometry of one iron atom/subunit. EPR spectroscopy of the colourless SOR resulted in a single isotropic signal at g=4.3, characteristic of high-spin ferric iron. The signal disappeared upon reduction with dithionite or incubation with sulphur at elevated temperature. Thus both EPR and chemical analysis indicate the presence of a mononuclear iron centre, which has a reduction potential of -268 mV at pH 6.5. Protein database inspection identified four SOR protein homologues, but no other significant similarities. The spectroscopic data and the sequence comparison led to the proposal that the Acidianus ambivalens SOR typifies a new type of non-haem iron enzyme containing a mononuclear iron centre co-ordinated by carboxylate and/or histidine ligands. << Less