Sulfation

Key takeaways

Sulfation belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Sulfation to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Sulfation from memory before moving on to harder problems.

Reference excerpt

Sulfation (sometimes spelled sulphation in British English) 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. The net reaction is:

CaO + SO2 → CaSO3 2 CaSO3 + O2 → 2 CaSO4 or the net reaction is sulfation, the addition of SO3:

CaO + SO3 → CaSO4 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 sodium lauryl sulfate and sodium laureth sulfate. Alkylsulfate are produced from alcohols by reaction with chlorosulfuric acid:

ClSO3H + ROH → ROSO3H + HCl Alternatively, alcohols can be sulfated to the half sulfate esters using sulfur trioxide. The reaction proceeds by initial formation of the pyrosulfate:

2 SO3 + RCH2OH → RCH2OSO2−O−SO3H RCH2OSO2−O−SO3H → RCH2OSO3H + SO3 Several million tons of fatty acid sulfates are produced in this way annually. The most common example is sodium dodecylsulfate (SDS) derived from lauryl alcohol.

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. 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. Sulfation is involved in a variety of biological processes, including detoxification, hormone regulation, molecular recognition, cell signaling, and viral entry into cells. 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). Sulfate is part of sulfolipids, such as sulfatides, which constitute 20% of the galactolipids in myelin. 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

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 occurs 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.

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.

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

See also Glucuronidation Methylation Hydrogenation Rosemary Waring Acetylation

References

Moore KL (2003). "The biology and enzymology of protein tyrosine O-sulfation". J. Biol. Chem. 278 (27): 24243–6. doi:10.1074/jbc.R300008200. 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. doi:10.1074/jbc.M609398200. PMC 1764208. PMID 17046811.

Worked examples

Example 1 — a first encounter with Sulfation

Start with the simplest possible case. Write down what Sulfation claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Sulfation before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Sulfation ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Sulfation

In research: Sulfation appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Sulfation in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Sulfation is common in secondary-school and first-year university syllabi. It links to neighbouring topics Post-translational modification, so understanding it makes those chapters shorter.
In everyday life: Look for Sulfation outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Sulfation in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Sulfation means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Sulfation out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Sulfation in simple terms?

Sulfation (sometimes spelled sulphation in British English) is the chemical reaction that entails the addition of SO3 group. In principle, many sulfations would involve reactions of sulfur trioxide (SO3).

Why does Sulfation matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Sulfation?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Sulfation.