MetaCyc Compound: S0

Synonyms: elemental sulfur, orthorhombic sulfur, rhombic sulfur

Superclasses: an inorganic compound

Elemental sulfur appears in a number of different allotropic modifications: rhombic, monoclinic, polymeric, and others. The rhombic structure is the most common. Both the rhombic and monoclinic forms of sulfur are made up of eight sulfur atoms arranged in a puckered-ring structure. At one atmosphere pressure and temperatures less than 95.4C, rhombic is the stable crystalline form. Above 95.4 C to the melt temperature of 118.9 C, the monoclinic crystalline structure is dominant [Steudel00].

In addition, elemental sulfur always contains some polymeric sulfur consisting of chain-like macromolecules. The S-S bond energy is lower in polymeric sulfur than in ring sulfur [Franz07].

Monoisotopic Molecular Weight: 31.97207069 Daltons


Unification Links: ChEBI:17909, KEGG:C00087

Standard Gibbs Free Energy of Change Formation (ΔfG in kcal/mol): 8.770001Inferred by computational analysis [Latendresse13]

Reactions known to consume the compound:

sulfur disproportionation I (anaerobic) :
3 S0 + 3 H2O → sulfite + 2 hydrogen sulfide + 2 H+

sulfur disproportionation II (aerobic) :
5 S0 + oxygen + 4 H2O → sulfite + thiosulfate + 2 hydrogen sulfide + 3 H+

sulfur oxidation I (aerobic) , sulfur oxidation II (Fe+3-dependent) :
S0 + glutathione → S-sulfanylglutathione

sulfur reduction I :
S0 + H2 → hydrogen sulfide

sulfur reduction II (via polysulfide) :
n S0 + HS- → (sulfide)n+1 + H+

Not in pathways:
hydrogen sulfide + NAD(P)+S0 + NAD(P)H + H+
4 S0 + 4 H2O + oxygen → 2 hydrogen sulfide + 2 sulfite + 4 H+

Reactions known to produce the compound:

glucosinolate breakdown (via thiocyanate-forming protein) :
benzylglucosinolate aglycone → S0 + phenylacetonitrile + sulfate

sulfide oxidation II (sulfide dehydrogenase) :
hydrogen sulfide + 2 an oxidized c-type cytochrome → S0 + 2 a reduced c-type cytochrome + 2 H+

tetrathionate oxidation :
tetrathionate + H2O → S0 + thiosulfate + sulfate + H+

tetrathionate reductiuon II (to trithionate) :
tetrathionate → S0 + trithionate

In Reactions of unknown directionality:

Not in pathways:
S0 + a sulfur-binding protein = a sulfurylated sulfur-binding protein

Enzymes inhibited by S0, sorted by the type of inhibition, are:

Inhibitor (Mechanism unknown) of: sulfide dehydrogenase [Quentmeier04]


Franz07: Franz B, Lichtenberg H, Hormes J, Modrow H, Dahl C, Prange A (2007). "Utilization of solid "elemental" sulfur by the phototrophic purple sulfur bacterium Allochromatium vinosum: a sulfur K-edge X-ray absorption spectroscopy study." Microbiology 153(Pt 4);1268-74. PMID: 17379736

Latendresse13: Latendresse M. (2013). "Computing Gibbs Free Energy of Compounds and Reactions in MetaCyc."

Quentmeier04: Quentmeier A, Hellwig P, Bardischewsky F, Wichmann R, Friedrich CG (2004). "Sulfide dehydrogenase activity of the monomeric flavoprotein SoxF of Paracoccus pantotrophus." Biochemistry 43(46);14696-703. PMID: 15544340

Steudel00: Steudel, R. (2000). "The chemical sulfur cycle." Environmental Technologies to Treat Sulfur Pollution, pp. 1-31. Edited by P. N. L. Lens & L. Hulshof Pol. London: IWA Publishing.

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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