Sulfation

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Sulfation is the chemical reaction that entails the addition of SO3 group. In principle, many sulfations would involve reactions of sulfur trioxide (SO3). In practice, most sulfations are effected less directly. Regardless of the mechanism, the installation of a sulfate-like group on a substrate leads to substantial changes.

Sulfation in industry[edit]

Sulfation of calcium oxides[edit]

Sulfation is a process used to remove "sulfur" from the combustion of fossil fuels. The goal is to minimize the pollution by the combusted gases. Combustion of sulfur-containing fuels releases sulfur dioxide, which, in the atmosphere, oxidizes to the equivalent of sulfuric acid, which is corrosive. To minimize the problem, the combustion is often conducted in the presence of calcium oxide or calcium carbonate, which, directly or indirectly, bind sulfur dioxide and some oxygen to give calcium sulfate.[1] The net reaction is:

CaO + SO2 → CaSO3
CaSO3 + 1/2 O2 → CaSO4

or the net reaction is sulfation, the addition of SO3:

CaO + SO3 → CaSO3

In the idealized scenario, the calcium sulfate (gypsum) is used as a construction material or, less desirably, deposited in a landfill.

Other inorganic sulfations[edit]

Detergents, cosmetics, etc.[edit]

Sulfation is widely used in the production of consumer products such as detergents, shampoos, and cosmetics. Since the sulfate group is highly polar, its conjugation to a lipophilic "tail" gives surfacant-like properties. Well known sulfates are sodium lauryl sulfate and sodium laureth sulfate.[2]

Alkylsulfate are produced from alcohols by reaction with chlorosulfuric acid:[3]

ClSO3H + ROH → ROSO3H + HCl

Alternatively, alcohols can be sulfated to the half sulfate esters using sulfur trioxide:[4]

SO3 + ROH → ROSO3H

Sulfation in biology[edit]

In biology, sulfation is typically effected by sulfotransferases, which catalyze the transfer of the equivalent of sulfur trioxide to substrate alcohols and phenols, converting the latter to sulfate esters. [5][6] The source of the SO3 group is usually 3'-phosphoadenosine-5'-phosphosulfate (PAPS). When the substrate is an amine, the result is a sulfamate. Sulfation is one of the principal routes for post-translational modification of proteins.[7]

Sulfation is involved in a variety of biological processes, including detoxification, hormone regulation, molecular recognition, cell signaling, and viral entry into cells.[6] It is among the reactions in phase II drug metabolism, frequently effective in rendering a xenobiotic less active from a pharmacological and toxicological standpoint, but sometimes playing a role in the activation of xenobiotics (e.g. aromatic amines, methyl-substituted polycyclic aromatic hydrocarbons). Another example of biological sulfation is in the synthesis of sulfonated glycosaminoglycans, such as heparin, heparan sulfate, chondroitin sulfate, and dermatan sulfate. Sulfation is also a possible posttranslational modification of proteins.

Tyrosine sulfation[edit]

Tyrosine sulfation is a posttranslational modification in which a tyrosine residue of a protein is sulfated by a tyrosylprotein sulfotransferase (TPST) typically in the Golgi apparatus. Secreted proteins and extracellular parts of membrane proteins that pass through the Golgi apparatus may be sulfated. Sulfation occurss in animals and plants but not in prokaryotes or in yeasts. Sulfation sites are tyrosine residues exposed on the surface of the protein typically surrounded by acidic residues. The function of sulfation remains uncertain.[7]

Regulation of tyrosine sulfation[edit]

Very limited evidence suggests that the TPST genes are subject to transcriptional regulation and tyrosine O-sulfate is very stable and cannot be easily degraded by mammalian sulfatases. Tyrosine O-sulfation is an irreversible process in vivo. An antibody called PSG2 shows high sensitivity and specificity for epitopes containing sulfotyrosine independent of the sequence context. New tools are being developed to study TPST's, using synthetic peptides and small molecule screens.[8]

Seagrasses[edit]

Many edible seaweeds are composed on highly sulfated polysaccharides.[9] The evolution of several sulfotransferases appears to have facilitated the adaptation of the terrestrial ancestors of seagrasses to a new marine habitat.[10][11]

See also[edit]

References[edit]

  1. ^ Anthony, E.J.; Granatstein, D.L. (2001). "Sulfation phenomena in fluidized bed combustion systems". Progress in Energy and Combustion Science. 27 (2): 215–236. doi:10.1016/S0360-1285(00)00021-6.
  2. ^ Eduard Smulders, Wolfgang von Rybinski, Eric Sung, Wilfried Rähse, Josef Steber, Frederike Wiebel, Anette Nordskog "Laundry Detergents" in Ullmann's Encyclopedia of Industrial Chemistry 2007, Wiley-VCH, Weinheim. doi:10.1002/14356007.a08_315.pub2.
  3. ^ Klaus Noweck, Wolfgang Grafahrend, "Fatty Alcohols" in Ullmann’s Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. doi:10.1002/14356007.a10_277.pub2
  4. ^ Kosswig, Kurt (2000). "Surfactants". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a25_747.
  5. ^ Glatt, Hansruedi (2000). "Sulfotransferases in the bioactivation of xenobiotics". Chemico-Biological Interactions. 129 (1–2): 141–170. doi:10.1016/S0009-2797(00)00202-7. PMID 11154739.
  6. ^ a b Chapman, Eli; Best, Michael D.; Hanson, Sarah R.; Wong, Chi-Huey (2004-07-05). "Sulfotransferases: Structure, Mechanism, Biological Activity, Inhibition, and Synthetic Utility". Angewandte Chemie International Edition. 43 (27): 3526–3548. doi:10.1002/anie.200300631. ISSN 1521-3773. PMID 15293241.
  7. ^ a b Walsh, Gary; Jefferis, Roy (2006). "Post-translational modifications in the context of therapeutic proteins". Nature Biotechnology. 24 (10): 1241–1252. doi:10.1038/nbt1252. PMID 17033665. S2CID 33899490.
  8. ^ Byrne, D. P. (2018). "New tools for evaluating protein tyrosine sulfation: tyrosylprotein sulfotransferases (TPSTs) are novel targets for RAF protein kinase inhibitors". Biochemical Journal. 475 (15): 2435–2455. doi:10.1042/BCJ20180266. PMC 6094398. PMID 29934490.
  9. ^ Jiao, Guangling; Yu, Guangli; Zhang, Junzeng; Ewart, H. (2011). "Chemical Structures and Bioactivities of Sulfated Polysaccharides from Marine Algae". Marine Drugs. 9 (2): 196–223. doi:10.3390/md9020196. PMC 3093253. PMID 21566795.
  10. ^ Olsen, Jeanine L.; et al. (2016). "The genome of the seagrass Zostera marina reveals angiosperm adaptation to the sea". Nature. 530 (7590): 331–335. Bibcode:2016Natur.530..331O. doi:10.1038/nature16548. PMID 26814964. S2CID 3713147.
  11. ^ Pfeifer, Lukas; Classen, Birgit (2020). "The Cell Wall of Seagrasses: Fascinating, Peculiar and a Blank Canvas for Future Research". Frontiers in Plant Science. 11: 588754. doi:10.3389/fpls.2020.588754. PMC 7644952. PMID 33193541.