Sulfation
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
Sulfation of calcium oxides
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 sulfite.[1] The net reaction is:
- CaO + SO2 → 3
- 2 CaSO3 + O2 → 2 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
Detergents, cosmetics, etc.
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
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
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.
Sulfation is involved in a variety of biological processes, including detoxification, hormone regulation, molecular recognition, cell signaling, and viral entry into cells.
Tyrosine sulfation
Tyrosine sulfation is a
Regulation of tyrosine sulfation
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
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
References
- Moore KL (2003). "The biology and enzymology of protein tyrosine O-sulfation". J. Biol. Chem. 278 (27): 24243–6. PMID 12730193.
- Hoffhines AJ; Damoc, E; Bridges, KG; Leary, JA; Moore, KL (2006). "Detection and purification of tyrosine-sulfated proteins using a novel anti-sulfotyrosine monoclonal antibody". J. Biol. Chem. 281 (49): 37877–87. PMID 17046811.
