2.0 2012-05-31 13:58:18 -0600 2015-09-13 12:56:12 -0600 ECMDB03276 M2MDB000486 Hydrogen sulfide Hydrogen sulfide is a highly toxic and flammable gas. Because it is heavier than air it tends to accumulate at the bottom of poorly ventilated spaces. Although very pungent at first, it quickly deadens the sense of smell, so potential victims may be unaware of its presence until it is too late. H2S arises from virtually anywhere where elemental sulfur comes into contact with organic material, especially at high temperatures. Hydrogen sulfide is a covalent hydride chemically related to water (H2O) since oxygen and sulfur occur in the same periodic table group. It often results when bacteria break down organic matter in the absence of oxygen, such as in swamps, and sewers (alongside the process of anaerobic digestion). It also occurs in volcanic gases, natural gas and some well waters. It is also important to note that Hydrogen sulfide is a central participant in the sulfur cycle, the biogeochemical cycle of sulfur on earth. As mentioned above, sulfur-reducing and sulfate-reducing bacteria derive energy from oxidizing hydrogen or organic molecules in the absence of oxygen by reducing sulfur or sulfate to hydrogen sulfide. Other bacteria liberate hydrogen sulfide from sulfur-containing amino acids. Several groups of bacteria can use hydrogen sulfide as fuel, oxidizing it to elemental sulfur or to sulfate by using oxygen or nitrate as oxidant. The purple sulfur bacteria and the green sulfur bacteria use hydrogen sulfide as electron donor in photosynthesis, thereby producing elemental sulfur. (In fact, this mode of photosynthesis is older than the mode of cyanobacteria, algae and plants which uses water as electron donor and liberates oxygen). Acide sulfhydrique Acide sulphhydrique Dihydrogen disulfide Dihydrogen disulphide Dihydrogen monosulfide Dihydrogen monosulphide Dihydrogen sulfide Dihydrogen sulphide H2S H<SUB>2</SUB>S Hepatate Hepatic acid Hepatic gas Hydrogen monosulfide Hydrogen monosulphide Hydrogen sulfide Hydrogen sulphide Hydrogen-sulfide Hydrogen-sulphide Hydrogene sulfure Hydrogene sulphure Hydrosulfate Hydrosulfurate Hydrosulfuric acid Hydrosulphate Hydrosulphurate Hydrosulphuric acid Idrogeno solforato Schwefelwasserstoff Sewer gas Siarkowodor Sour gas Stink dAMP Sulfide Sulfur hydride Sulfur hydroxide Sulfureted hydrogen Sulfuretted hydrogen Sulphide Sulphur hydride Sulphur hydroxide Sulphureted hydrogen Sulphuretted hydrogen Zwavelwaterstof H2S 34.081 33.987720754 hydrogen sulfide hydrogen sulfide 7783-06-4 S InChI=1S/H2S/h1H2 RWSOTUBLDIXVET-UHFFFAOYSA-N Liquid Cytosol Extra-organism Periplasm melting_point -85.49 oC logp -0.037 ChemAxon iupac hydrogen sulfide ChemAxon average_mass 34.081 ChemAxon mono_mass 33.987720754 ChemAxon smiles S ChemAxon formula H2S ChemAxon inchi InChI=1S/H2S/h1H2 ChemAxon inchikey RWSOTUBLDIXVET-UHFFFAOYSA-N ChemAxon polar_surface_area 0 ChemAxon refractivity 7.36 ChemAxon polarizability 3.45 ChemAxon rotatable_bond_count 0 ChemAxon acceptor_count 0 ChemAxon donor_count 1 ChemAxon physiological_charge -1 ChemAxon formal_charge 0 ChemAxon Cysteine and methionine metabolism ec00270 Selenoamino acid metabolism ec00450 Sulfur metabolism The sulfur metabolism pathway starts in three possible ways. The first is the uptake of sulfate through an active transport reaction via a sulfate transport system containing an ATP-binding protein which hydrolyses ATP. Sulfate is converted by the sulfate adenylyltransferase enzymatic complex to adenosine phosphosulfate through the addition of adenine from a molecule of ATP, along with one phosphate group. Adenosine phosphosulfate is further converted to phoaphoadenosine phosphosulfate through an ATP hydrolysis and dehydrogenation reaction by the adenylyl-sulfate kinase. Phoaphoadenosine phosphosulfate is finally dehydrogenated and converted to sulfite by phosphoadenosine phosphosulfate reductase. This reaction requires magnesium, and adenosine 3',5'-diphosphate is the bi-product. A thioredoxin is also oxidized. Sulfite can also be produced from the dehydrogenation of cyanide along with the conversion of thiosulfate to thiocyanate by the thiosulfate sulfurtransferase enzymatic complex. Sulfite next undergoes a series of reactions that lead to the production of pyruvic acid, which is a precursor for pathways such as gluconeogenesis. The first reaction in this series is the conversion of sulfite to hydrogen sulfide through hygrogenation and the deoxygenation of sulfite to form a water molecule. The reaction is catalyzed by the sulfite reductase [NADPH] flavoprotein alpha and beta components. Siroheme, 4Fe-4S, flavin mononucleotide, and FAD function as cofactors or prosthetic groups. Hydrogen sulfide next undergoes dehydrogenation in a reversible reaction to form L-Cysteine and acetic acid, via the cysteine synthase complex and the coenzyme pyridoxal 5'-phosphate. L-Cysteine is dehydrogenated and converted to 2-aminoacrylic acid (a bronsted acid) and hydrogen sulfide(which may be reused) by a larger enzymatic complex composed of cysteine synthase A/B, protein malY, cystathionine-β-lyase, and tryptophanase, along with the coenzyme pyridoxal 5'-phosphate. 2-aminoacrylic acid isomerizes to 2-iminopropanoate, which along with a water molecule and a hydrogen ion is lastly converted to pyruvic acid and ammonium in a spontaneous fashion. The second possible initial starting point for sulfur metabolism is the import of taurine(an alternate sulfur source) into the cytoplasm via the taurine ABC transporter complex. Taurine, oxoglutaric acid, and oxygen are converted to sulfite by the alpha-ketoglutarate-dependent taurine dioxygenase. Carbon dioxide, succinic acid, and aminoacetaldehyde are bi-products of this reaction. Sulfite next enters pyruvic acid synthesis as already described. The third variant of sulfur metabolism starts with the import of an alkyl sulfate into the cytoplasm via an aliphatic sulfonate ABC transporter complex which hydrolyses ATP. The alkyl sulfate is dehydrogenated and along with oxygen is converted to sulfite and an aldehyde by the FMNH2-dependent alkanesulfonate monooxygenase enzyme. Water and flavin mononucleotide(which is used in a subsequent reaction as a prosthetic group) are also produced. Sulfite is next converted to pyruvic acid by the process already described. PW000922 ec00920 Metabolic Microbial metabolism in diverse environments ec01120 Metabolic pathways eco01100 Secondary Metabolites: cysteine biosynthesis from serine The pathway starts with a 3-phosphoglyceric acid interacting with an NAD driven D-3-phosphoglycerate dehydrogenase / α-ketoglutarate reductase resulting in an NADH, a hydrogen ion and a phosphohydroxypyruvic acid. This compound then interacts with an L-glutamic acid through a 3-phosphoserine aminotransferase / phosphohydroxythreonine aminotransferase resulting in a oxoglutaric acid and a DL-D-phosphoserine. The latter compound then interacts with a water molecule through a phosphoserine phosphatase resulting in a phosphate and an L-serine. The L-serine interacts with an acetyl-coa through a serine acetyltransferase resulting in a release of a Coenzyme A and a O-Acetylserine. The O-acetylserine then interacts with a hydrogen sulfide through a O-acetylserine sulfhydrylase A resulting in an acetic acid, a hydrogen ion and an L-cysteine PW000977 Metabolic cysteine biosynthesis The pathway of cysteine biosynthesis is a two-step conversion starting from L-serine and yielding L-cysteine. L-serine biosynthesis is shown for context. L-cysteine can also be synthesized from sulfate derivatives. The process through L-serine involves a serine acetyltransferase that produces a O-acetylserine which reacts together with hydrogen sulfide through a cysteine synthase complex in order to produce L-cysteine and acetic acid. Hydrogen sulfide is produced from a sulfate. Sulfate reacts with sulfate adenylyltransferase to produce adenosine phosphosulfate. This compound in turn is phosphorylated through a adenylyl-sulfate kinase into a phosphoadenosine phosphosulfate which in turn reacts with a phosphoadenosine phosphosulfate reductase to produce a sulfite. The sulfite reacts with a sulfite reductase to produce the hydrogen sulfide. This pathway is regulated at the genetic level in its second step, wtih both cysteine synthase isozymes being under the positive control of the cysteine-responsive transcription factor CysB. It is also subject to very strong feedback inhibition of its first step by the final pathway product, cysteine. Although two cysteine synthase isozymes exist, only cysteine synthase A (CysK) forms a complex with serine acetyltransferase. CysK is also the only one of the two cysteine synthases that is required for cell viability on cysteine-free medium. Both steps in this pathway are reversible. Based on genetic and proteomic data, it appears that the cysteine synthases may actually act as a sulfur scavenging system during sulfur starvation, stripping sulfur off of L-cysteine, generating any number of variant amino acids in the process. PW000800 Metabolic sulfur metabolism (butanesulfonate) The sulfur metabolism pathway starts in three possible ways. The first is the uptake of sulfate through an active transport reaction via a sulfate transport system containing an ATP-binding protein which hydrolyses ATP. Sulfate is converted by the sulfate adenylyltransferase enzymatic complex to adenosine phosphosulfate through the addition of adenine from a molecule of ATP, along with one phosphate group. Adenosine phosphosulfate is further converted to phoaphoadenosine phosphosulfate through an ATP hydrolysis and dehydrogenation reaction by the adenylyl-sulfate kinase. Phoaphoadenosine phosphosulfate is finally dehydrogenated and converted to sulfite by phosphoadenosine phosphosulfate reductase. This reaction requires magnesium, and adenosine 3',5'-diphosphate is the bi-product. A thioredoxin is also oxidized. Sulfite can also be produced from the dehydrogenation of cyanide along with the conversion of thiosulfate to thiocyanate by the thiosulfate sulfurtransferase enzymatic complex. Sulfite next undergoes a series of reactions that lead to the production of pyruvic acid, which is a precursor for pathways such as gluconeogenesis. The first reaction in this series is the conversion of sulfite to hydrogen sulfide through hygrogenation and the deoxygenation of sulfite to form a water molecule. The reaction is catalyzed by the sulfite reductase [NADPH] flavoprotein alpha and beta components. Siroheme, 4Fe-4S, flavin mononucleotide, and FAD function as cofactors or prosthetic groups. Hydrogen sulfide next undergoes dehydrogenation in a reversible reaction to form L-Cysteine and acetic acid, via the cysteine synthase complex and the coenzyme pyridoxal 5'-phosphate. L-Cysteine is dehydrogenated and converted to 2-aminoacrylic acid (a bronsted acid) and hydrogen sulfide(which may be reused) by a larger enzymatic complex composed of cysteine synthase A/B, protein malY, cystathionine-β-lyase, and tryptophanase, along with the coenzyme pyridoxal 5'-phosphate. 2-aminoacrylic acid isomerizes to 2-iminopropanoate, which along with a water molecule and a hydrogen ion is lastly converted to pyruvic acid and ammonium in a spontaneous fashion. The second possible initial starting point for sulfur metabolism is the import of taurine(an alternate sulfur source) into the cytoplasm via the taurine ABC transporter complex. Taurine, oxoglutaric acid, and oxygen are converted to sulfite by the alpha-ketoglutarate-dependent taurine dioxygenase. Carbon dioxide, succinic acid, and aminoacetaldehyde are bi-products of this reaction. Sulfite next enters pyruvic acid synthesis as already described. The third variant of sulfur metabolism starts with the import of an alkyl sulfate, in this case 1-butanesulfonate, into the cytoplasm via an aliphatic sulfonate ABC transporter complex which hydrolyses ATP. 1-butanesulfonate is dehydrogenated and along with oxygen is converted to sulfite and betaine aldehyde by the FMNH2-dependent alkanesulfonate monooxygenase enzyme. Water and flavin mononucleotide(which is used in a subsequent reaction as a prosthetic group) are also produced. Sulfite is next converted to pyruvic acid by the process already described. PW000923 Metabolic sulfur metabolism (ethanesulfonate) The sulfur metabolism pathway starts in three possible ways. The first is the uptake of sulfate through an active transport reaction via a sulfate transport system containing an ATP-binding protein which hydrolyses ATP. Sulfate is converted by the sulfate adenylyltransferase enzymatic complex to adenosine phosphosulfate through the addition of adenine from a molecule of ATP, along with one phosphate group. Adenosine phosphosulfate is further converted to phoaphoadenosine phosphosulfate through an ATP hydrolysis and dehydrogenation reaction by the adenylyl-sulfate kinase. Phoaphoadenosine phosphosulfate is finally dehydrogenated and converted to sulfite by phosphoadenosine phosphosulfate reductase. This reaction requires magnesium, and adenosine 3',5'-diphosphate is the bi-product. A thioredoxin is also oxidized. Sulfite can also be produced from the dehydrogenation of cyanide along with the conversion of thiosulfate to thiocyanate by the thiosulfate sulfurtransferase enzymatic complex. Sulfite next undergoes a series of reactions that lead to the production of pyruvic acid, which is a precursor for pathways such as gluconeogenesis. The first reaction in this series is the conversion of sulfite to hydrogen sulfide through hygrogenation and the deoxygenation of sulfite to form a water molecule. The reaction is catalyzed by the sulfite reductase [NADPH] flavoprotein alpha and beta components. Siroheme, 4Fe-4S, flavin mononucleotide, and FAD function as cofactors or prosthetic groups. Hydrogen sulfide next undergoes dehydrogenation in a reversible reaction to form L-Cysteine and acetic acid, via the cysteine synthase complex and the coenzyme pyridoxal 5'-phosphate. L-Cysteine is dehydrogenated and converted to 2-aminoacrylic acid (a bronsted acid) and hydrogen sulfide(which may be reused) by a larger enzymatic complex composed of cysteine synthase A/B, protein malY, cystathionine-β-lyase, and tryptophanase, along with the coenzyme pyridoxal 5'-phosphate. 2-aminoacrylic acid isomerizes to 2-iminopropanoate, which along with a water molecule and a hydrogen ion is lastly converted to pyruvic acid and ammonium in a spontaneous fashion. The second possible initial starting point for sulfur metabolism is the import of taurine(an alternate sulfur source) into the cytoplasm via the taurine ABC transporter complex. Taurine, oxoglutaric acid, and oxygen are converted to sulfite by the alpha-ketoglutarate-dependent taurine dioxygenase. Carbon dioxide, succinic acid, and aminoacetaldehyde are bi-products of this reaction. Sulfite next enters pyruvic acid synthesis as already described. The third variant of sulfur metabolism starts with the import of an alkyl sulfate, in this case ethanesulfonate, into the cytoplasm via an aliphatic sulfonate ABC transporter complex which hydrolyses ATP. Ethanesulfonate is dehydrogenated and along with oxygen is converted to sulfite and betaine aldehyde by the FMNH2-dependent alkanesulfonate monooxygenase enzyme. Water and flavin mononucleotide(which is used in a subsequent reaction as a prosthetic group) are also produced. Sulfite is next converted to pyruvic acid by the process already described. PW000925 Metabolic sulfur metabolism (isethionate) The sulfur metabolism pathway starts in three possible ways. The first is the uptake of sulfate through an active transport reaction via a sulfate transport system containing an ATP-binding protein which hydrolyses ATP. Sulfate is converted by the sulfate adenylyltransferase enzymatic complex to adenosine phosphosulfate through the addition of adenine from a molecule of ATP, along with one phosphate group. Adenosine phosphosulfate is further converted to phoaphoadenosine phosphosulfate through an ATP hydrolysis and dehydrogenation reaction by the adenylyl-sulfate kinase. Phoaphoadenosine phosphosulfate is finally dehydrogenated and converted to sulfite by phosphoadenosine phosphosulfate reductase. This reaction requires magnesium, and adenosine 3',5'-diphosphate is the bi-product. A thioredoxin is also oxidized. Sulfite can also be produced from the dehydrogenation of cyanide along with the conversion of thiosulfate to thiocyanate by the thiosulfate sulfurtransferase enzymatic complex. Sulfite next undergoes a series of reactions that lead to the production of pyruvic acid, which is a precursor for pathways such as gluconeogenesis. The first reaction in this series is the conversion of sulfite to hydrogen sulfide through hygrogenation and the deoxygenation of sulfite to form a water molecule. The reaction is catalyzed by the sulfite reductase [NADPH] flavoprotein alpha and beta components. Siroheme, 4Fe-4S, flavin mononucleotide, and FAD function as cofactors or prosthetic groups. Hydrogen sulfide next undergoes dehydrogenation in a reversible reaction to form L-Cysteine and acetic acid, via the cysteine synthase complex and the coenzyme pyridoxal 5'-phosphate. L-Cysteine is dehydrogenated and converted to 2-aminoacrylic acid (a bronsted acid) and hydrogen sulfide(which may be reused) by a larger enzymatic complex composed of cysteine synthase A/B, protein malY, cystathionine-β-lyase, and tryptophanase, along with the coenzyme pyridoxal 5'-phosphate. 2-aminoacrylic acid isomerizes to 2-iminopropanoate, which along with a water molecule and a hydrogen ion is lastly converted to pyruvic acid and ammonium in a spontaneous fashion. The second possible initial starting point for sulfur metabolism is the import of taurine(an alternate sulfur source) into the cytoplasm via the taurine ABC transporter complex. Taurine, oxoglutaric acid, and oxygen are converted to sulfite by the alpha-ketoglutarate-dependent taurine dioxygenase. Carbon dioxide, succinic acid, and aminoacetaldehyde are bi-products of this reaction. Sulfite next enters pyruvic acid synthesis as already described. The third variant of sulfur metabolism starts with the import of an alkyl sulfate, in this case isethionate, into the cytoplasm via an aliphatic sulfonate ABC transporter complex which hydrolyses ATP. Isethionate is dehydrogenated and along with oxygen is converted to sulfite and betaine aldehyde by the FMNH2-dependent alkanesulfonate monooxygenase enzyme. Water and flavin mononucleotide(which is used in a subsequent reaction as a prosthetic group) are also produced. Sulfite is next converted to pyruvic acid by the process already described. PW000926 Metabolic sulfur metabolism (methanesulfonate) The sulfur metabolism pathway starts in three possible ways. The first is the uptake of sulfate through an active transport reaction via a sulfate transport system containing an ATP-binding protein which hydrolyses ATP. Sulfate is converted by the sulfate adenylyltransferase enzymatic complex to adenosine phosphosulfate through the addition of adenine from a molecule of ATP, along with one phosphate group. Adenosine phosphosulfate is further converted to phoaphoadenosine phosphosulfate through an ATP hydrolysis and dehydrogenation reaction by the adenylyl-sulfate kinase. Phoaphoadenosine phosphosulfate is finally dehydrogenated and converted to sulfite by phosphoadenosine phosphosulfate reductase. This reaction requires magnesium, and adenosine 3',5'-diphosphate is the bi-product. A thioredoxin is also oxidized. Sulfite can also be produced from the dehydrogenation of cyanide along with the conversion of thiosulfate to thiocyanate by the thiosulfate sulfurtransferase enzymatic complex. Sulfite next undergoes a series of reactions that lead to the production of pyruvic acid, which is a precursor for pathways such as gluconeogenesis. The first reaction in this series is the conversion of sulfite to hydrogen sulfide through hygrogenation and the deoxygenation of sulfite to form a water molecule. The reaction is catalyzed by the sulfite reductase [NADPH] flavoprotein alpha and beta components. Siroheme, 4Fe-4S, flavin mononucleotide, and FAD function as cofactors or prosthetic groups. Hydrogen sulfide next undergoes dehydrogenation in a reversible reaction to form L-Cysteine and acetic acid, via the cysteine synthase complex and the coenzyme pyridoxal 5'-phosphate. L-Cysteine is dehydrogenated and converted to 2-aminoacrylic acid (a bronsted acid) and hydrogen sulfide(which may be reused) by a larger enzymatic complex composed of cysteine synthase A/B, protein malY, cystathionine-β-lyase, and tryptophanase, along with the coenzyme pyridoxal 5'-phosphate. 2-aminoacrylic acid isomerizes to 2-iminopropanoate, which along with a water molecule and a hydrogen ion is lastly converted to pyruvic acid and ammonium in a spontaneous fashion. The second possible initial starting point for sulfur metabolism is the import of taurine(an alternate sulfur source) into the cytoplasm via the taurine ABC transporter complex. Taurine, oxoglutaric acid, and oxygen are converted to sulfite by the alpha-ketoglutarate-dependent taurine dioxygenase. Carbon dioxide, succinic acid, and aminoacetaldehyde are bi-products of this reaction. Sulfite next enters pyruvic acid synthesis as already described. The third variant of sulfur metabolism starts with the import of an alkyl sulfate, in this case methanesulfonate, into the cytoplasm via an aliphatic sulfonate ABC transporter complex which hydrolyses ATP. Methanesulfonate is dehydrogenated and along with oxygen is converted to sulfite and an aldehyde by the FMNH2-dependent alkanesulfonate monooxygenase enzyme. Water and flavin mononucleotide(which is used in a subsequent reaction as a prosthetic group) are also produced. Sulfite is next converted to pyruvic acid by the process already described. PW000927 Metabolic sulfur metabolism (propanesulfonate) The sulfur metabolism pathway starts in three possible ways. The first is the uptake of sulfate through an active transport reaction via a sulfate transport system containing an ATP-binding protein which hydrolyses ATP. Sulfate is converted by the sulfate adenylyltransferase enzymatic complex to adenosine phosphosulfate through the addition of adenine from a molecule of ATP, along with one phosphate group. Adenosine phosphosulfate is further converted to phoaphoadenosine phosphosulfate through an ATP hydrolysis and dehydrogenation reaction by the adenylyl-sulfate kinase. Phoaphoadenosine phosphosulfate is finally dehydrogenated and converted to sulfite by phosphoadenosine phosphosulfate reductase. This reaction requires magnesium, and adenosine 3',5'-diphosphate is the bi-product. A thioredoxin is also oxidized. Sulfite can also be produced from the dehydrogenation of cyanide along with the conversion of thiosulfate to thiocyanate by the thiosulfate sulfurtransferase enzymatic complex. Sulfite next undergoes a series of reactions that lead to the production of pyruvic acid, which is a precursor for pathways such as gluconeogenesis. The first reaction in this series is the conversion of sulfite to hydrogen sulfide through hygrogenation and the deoxygenation of sulfite to form a water molecule. The reaction is catalyzed by the sulfite reductase [NADPH] flavoprotein alpha and beta components. Siroheme, 4Fe-4S, flavin mononucleotide, and FAD function as cofactors or prosthetic groups. Hydrogen sulfide next undergoes dehydrogenation in a reversible reaction to form L-Cysteine and acetic acid, via the cysteine synthase complex and the coenzyme pyridoxal 5'-phosphate. L-Cysteine is dehydrogenated and converted to 2-aminoacrylic acid (a bronsted acid) and hydrogen sulfide(which may be reused) by a larger enzymatic complex composed of cysteine synthase A/B, protein malY, cystathionine-β-lyase, and tryptophanase, along with the coenzyme pyridoxal 5'-phosphate. 2-aminoacrylic acid isomerizes to 2-iminopropanoate, which along with a water molecule and a hydrogen ion is lastly converted to pyruvic acid and ammonium in a spontaneous fashion. The second possible initial starting point for sulfur metabolism is the import of taurine(an alternate sulfur source) into the cytoplasm via the taurine ABC transporter complex. Taurine, oxoglutaric acid, and oxygen are converted to sulfite by the alpha-ketoglutarate-dependent taurine dioxygenase. Carbon dioxide, succinic acid, and aminoacetaldehyde are bi-products of this reaction. Sulfite next enters pyruvic acid synthesis as already described. The third variant of sulfur metabolism starts with the import of an alkyl sulfate, in this case 3-(N-morpholino)propanesulfonate, into the cytoplasm via an aliphatic sulfonate ABC transporter complex which hydrolyses ATP. 3-(N-morpholino)propanesulfonate is dehydrogenated and along with oxygen is converted to sulfite and betaine aldehyde by the FMNH2-dependent alkanesulfonate monooxygenase enzyme. Water and flavin mononucleotide(which is used in a subsequent reaction as a prosthetic group) are also produced. Sulfite is next converted to pyruvic acid by the process already described. PW000924 Metabolic Hydrogen Sulfide Biosynthesis I It has long been known that many bacteria are able to produce hydrogen sulfide [Barrett87]. However, the physiological role of H2S in nonsulfur bacteria was unknown. A recent report has now shown that production of H2S serves to defend cells from antibiotics by mitigating oxidative stress. This pathway is one of two pathways for hydrogen sulfide biosynthesis. Neither of the two activities have been shown biochemically for the E. coli enzymes. The function of AspC as a cysteine transaminase is hypothesized based on sequence similarity to mammalian enzymes. The function of SseA was determined based on the phenotype of an sseA null mutant, which does not produce hydrogen sulfide. PW002066 Metabolic L-cysteine degradation The degradation of cysteine starts with L-cysteine reacting with l-cysteine desulfhydrase resulting in the release of a hydrogen sulfide, a hydrogen ion and a a 2-aminoprop-2-enoate. The latter compound in turn reacts spontaneously to form a 2-iminopropanoate. This compound in turn reacts spontaneously with water and a hydrogen ion resulting in the release of ammonium and pyruvate. PW002110 Metabolic cysteine biosynthesis I CYSTSYN-PWY L-cysteine degradation II LCYSDEG-PWY sulfate reduction I (assimilatory) SO4ASSIM-PWY hydrogen sulfide biosynthesis PWY0-1534 Specdb::CMs 894 Specdb::CMs 2986 Specdb::CMs 31448 Specdb::CMs 131721 Specdb::CMs 139455 Specdb::EiMs 1907 Specdb::NmrOneD 3980 Specdb::NmrOneD 135540 Specdb::NmrOneD 135541 Specdb::NmrOneD 135542 Specdb::NmrOneD 135543 Specdb::NmrOneD 135544 Specdb::NmrOneD 135545 Specdb::NmrOneD 135546 Specdb::NmrOneD 135547 Specdb::NmrOneD 135548 Specdb::NmrOneD 135549 Specdb::MsMs 20495 Specdb::MsMs 20496 Specdb::MsMs 20497 Specdb::MsMs 20879 Specdb::MsMs 20880 Specdb::MsMs 20881 Specdb::MsMs 22046 Specdb::MsMs 22047 Specdb::MsMs 22048 Specdb::MsMs 22430 Specdb::MsMs 22431 Specdb::MsMs 22432 Specdb::MsMs 2456394 Specdb::MsMs 2456395 Specdb::MsMs 2456396 Specdb::MsMs 2479306 Specdb::MsMs 2479307 Specdb::MsMs 2479308 HMDB03276 402 391 C00283 16136 HS S Hydrogen sulfide Keseler, I. M., Collado-Vides, J., Santos-Zavaleta, A., Peralta-Gil, M., Gama-Castro, S., Muniz-Rascado, L., Bonavides-Martinez, C., Paley, S., Krummenacker, M., Altman, T., Kaipa, P., Spaulding, A., Pacheco, J., Latendresse, M., Fulcher, C., Sarker, M., Shearer, A. G., Mackie, A., Paulsen, I., Gunsalus, R. P., Karp, P. D. (2011). "EcoCyc: a comprehensive database of Escherichia coli biology." Nucleic Acids Res 39:D583-D590. 21097882 Kanehisa, M., Goto, S., Sato, Y., Furumichi, M., Tanabe, M. (2012). "KEGG for integration and interpretation of large-scale molecular data sets." Nucleic Acids Res 40:D109-D114. 22080510 Winder, C. L., Dunn, W. B., Schuler, S., Broadhurst, D., Jarvis, R., Stephens, G. M., Goodacre, R. (2008). "Global metabolic profiling of Escherichia coli cultures: an evaluation of methods for quenching and extraction of intracellular metabolites." Anal Chem 80:2939-2948. 18331064 Jiang T, Suarez FL, Levitt MD, Nelson SE, Ziegler EE: Gas production by feces of infants. J Pediatr Gastroenterol Nutr. 2001 May;32(5):534-41. 11429513 Boehning D, Snyder SH: Novel neural modulators. Annu Rev Neurosci. 2003;26:105-31. 14527267 Kresimon J, Gruter UM, Hirner AV: HG/LT-GC/ICP-MS coupling for identification of metal(loid) species in human urine after fish consumption. Fresenius J Anal Chem. 2001 Nov;371(5):586-90. 11767883 Kage S, Takekawa K, Kurosaki K, Imamura T, Kudo K: The usefulness of thiosulfate as an indicator of hydrogen sulfide poisoning: three cases. Int J Legal Med. 1997;110(4):220-2. 9274948 Kaplan WD, Piez CW, Gelman RS, Laffin SM, Rosenbaum EM, Jennings CA, McCormick CA, Harris JR, Henderson IC, Atkins HL: Clinical comparison of two radiocolloids for internal mammary lymphoscintigraphy. J Nucl Med. 1985 Dec;26(12):1382-5. 4067640 Naidong W, Shou WZ, Addison T, Maleki S, Jiang X: Liquid chromatography/tandem mass spectrometric bioanalysis using normal-phase columns with aqueous/organic mobile phases - a novel approach of eliminating evaporation and reconstitution steps in 96-well SPE. Rapid Commun Mass Spectrom. 2002;16(20):1965-75. 12362389 Claesson R, Granlund-Edstedt M, Persson S, Carlsson J: Activity of polymorphonuclear leukocytes in the presence of sulfide. Infect Immun. 1989 Sep;57(9):2776-81. 2547720 Quirynen M, Zhao H, Avontroodt P, Soers C, Pauwels M, Coucke W, van Steenberghe D: A salivary incubation test for evaluation of oral malodor: a pilot study. J Periodontol. 2003 Jul;74(7):937-44. 12931755 Donham KJ, Zejda JE: Lung dysfunction in animal confinement workers--chairman's report to the Scientific Committee of the Third International Symposium: issues in health, safety and agriculture, held in Saskatoon, Saskatchewan, Canada, May 10-15, 1992. Pol J Occup Med Environ Health. 1992;5(3):277-9. 1362681 Reid JS, Beeley JA, MacDonald DG: Investigations into black extrinsic tooth stain. J Dent Res. 1977 Aug;56(8):895-9. 270488 Chen X, Jhee KH, Kruger WD: Production of the neuromodulator H2S by cystathionine beta-synthase via the condensation of cysteine and homocysteine. J Biol Chem. 2004 Dec 10;279(50):52082-6. Epub 2004 Nov 1. 15520012 Warren YA, Citron DM, Merriam CV, Goldstein EJ: Biochemical differentiation and comparison of Desulfovibrio species and other phenotypically similar genera. J Clin Microbiol. 2005 Aug;43(8):4041-5. 16081948 Livermore A, Hummel T, Kobal G: Chemosensory event-related potentials in the investigation of interactions between the olfactory and the somatosensory (trigeminal) systems. Electroencephalogr Clin Neurophysiol. 1992 Sep;83(3):201-10. 1381671 Xu C, Li CY, Kong AN: Induction of phase I, II and III drug metabolism/transport by xenobiotics. Arch Pharm Res. 2005 Mar;28(3):249-68. 15832810 Jorgensen J, Mortensen PB: Hydrogen sulfide and colonic epithelial metabolism: implications for ulcerative colitis. Dig Dis Sci. 2001 Aug;46(8):1722-32. 11508674 Kage S, Ito S, Kishida T, Kudo K, Ikeda N: A fatal case of hydrogen sulfide poisoning in a geothermal power plant. J Forensic Sci. 1998 Jul;43(4):908-10. 9670519 Kage S, Kashimura S, Ikeda H, Kudo K, Ikeda N: Fatal and nonfatal poisoning by hydrogen sulfide at an industrial waste site. J Forensic Sci. 2002 May;47(3):652-5. 12051356 http://hmdb.ca/system/metabolites/msds/000/002/859/original/HMDB03276.pdf?1358462949 Cystathionine gamma-synthase P00935 METB_ECOLI metB http://ecmdb.ca/proteins/P00935.xml Cystathionine beta-lyase metC P06721 METC_ECOLI metC http://ecmdb.ca/proteins/P06721.xml Tryptophanase P0A853 TNAA_ECOLI tnaA http://ecmdb.ca/proteins/P0A853.xml Cysteine synthase A P0ABK5 CYSK_ECOLI cysK http://ecmdb.ca/proteins/P0ABK5.xml Biotin synthase P12996 BIOB_ECOLI bioB http://ecmdb.ca/proteins/P12996.xml Cysteine synthase B P16703 CYSM_ECOLI cysM http://ecmdb.ca/proteins/P16703.xml Sulfite reductase [NADPH] hemoprotein beta-component P17846 CYSI_ECOLI cysI http://ecmdb.ca/proteins/P17846.xml Protein malY P23256 MALY_ECOLI malY http://ecmdb.ca/proteins/P23256.xml 3-mercaptopyruvate sulfurtransferase P31142 THTM_ECOLI sseA http://ecmdb.ca/proteins/P31142.xml Sulfite reductase [NADPH] flavoprotein alpha-component P38038 CYSJ_ECOLI cysJ http://ecmdb.ca/proteins/P38038.xml Lipoyl synthase P60716 LIPA_ECOLI lipA http://ecmdb.ca/proteins/P60716.xml D-cysteine desulfhydrase P76316 DCYD_ECOLI dcyD http://ecmdb.ca/proteins/P76316.xml Outer membrane protein N P77747 OMPN_ECOLI ompN http://ecmdb.ca/proteins/P77747.xml Outer membrane pore protein E P02932 PHOE_ECOLI phoE http://ecmdb.ca/proteins/P02932.xml Outer membrane protein F P02931 OMPF_ECOLI ompF http://ecmdb.ca/proteins/P02931.xml Outer membrane protein C P06996 OMPC_ECOLI ompC http://ecmdb.ca/proteins/P06996.xml Protein PhsC homolog P77409 PHSC_ECOLI ydhU http://ecmdb.ca/proteins/P77409.xml O-Acetylserine + Hydrogen sulfide <> Acetic acid + L-Cysteine + Hydrogen ion R00897 ACSERLY-RXN 5 Hydrogen ion + 3 NADPH + Sulfite <>3 Water + Hydrogen sulfide +3 NADP R00858 SULFITE-REDUCT-RXN L-Cysteine + Water > Hydrogen sulfide + Ammonium + Pyruvic acid D-Cysteine + Water > Hydrogen sulfide + Ammonium + Pyruvic acid L-Cysteine + Water <> Hydrogen sulfide + Pyruvic acid + Ammonia R00782 LCYSDESULF-RXN Hydrogen sulfide + 3 NADP + 3 Water <> Sulfite +3 NADPH +3 Hydrogen ion R00858 O-Acetylserine + Hydrogen sulfide <> L-Cysteine + Acetic acid R00897 O-Succinyl-L-homoserine + Hydrogen sulfide <> L-Homocysteine + Succinic acid R01288 D-Cysteine + Water <> Hydrogen sulfide + Ammonia + Pyruvic acid R01874 Hydrogen ion + 3-Mercaptopyruvic acid > Pyruvic acid + Hydrogen sulfide RXN0-6945 D-Cysteine + Water <> Pyruvic acid + Hydrogen sulfide + Ammonia + Hydrogen ion R01874 DCYSDESULF-RXN L-Cysteine + Water > Pyruvic acid + Ammonia + Hydrogen sulfide + Hydrogen ion LCYSDESULF-RXN Water + NADP + Hydrogen sulfide < Hydrogen ion + NADPH + Sulfite SULFITE-REDUCT-RXN Dethiobiotin + Hydrogen sulfide + 2 S-adenosyl-L-methionine > Biotin +2 L-Methionine +2 5'-Deoxyadenosine Hydrogen sulfide + 3 NADP + 3 Water > Sulfite +3 NADPH O-Acetylserine + Hydrogen sulfide > L-Cysteine + Acetic acid D-Cysteine + Water > Hydrogen sulfide + Ammonia + Pyruvic acid Protein N(6)-(octanoyl)lysine + 2 Hydrogen sulfide + 2 S-adenosyl-L-methionine > protein N(6)-(lipoyl)lysine +2 L-Methionine +2 5'-Deoxyadenosine O-Acetylserine + Hydrogen sulfide > Hydrogen ion + Acetic acid + L-Cysteine PW_R002848 L-Cysteine > Hydrogen ion + Hydrogen sulfide + 2-Aminoacrylic acid PW_R003466 3 NADPH + 5 Hydrogen ion + Sulfite + 3 NADPH + Sulfite > Hydrogen sulfide +3 Water +3 NADP PW_R002849 Sulfite + 3 NADPH + 5 Hydrogen ion + Sulfite + 3 NADPH >3 Water + NADP + Hydrogen sulfide PW_R003464 3-Mercaptopyruvic acid > Pyruvic acid + Hydrogen sulfide PW_R006040 L-Cysteine > Hydrogen sulfide + Hydrogen ion + 2-aminoprop-2-enoate PW_R006145 O-Acetylserine + Hydrogen sulfide <> Acetic acid + L-Cysteine + Hydrogen ion 5 Hydrogen ion + 3 NADPH + Sulfite <>3 Water + Hydrogen sulfide +3 NADP O-Acetylserine + Hydrogen sulfide <> L-Cysteine + Acetic acid 5 Hydrogen ion + 3 NADPH + Sulfite <>3 Water + Hydrogen sulfide +3 NADP