chemistry

S-Methylmethionine

S-Methylmethionine is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand S-Methylmethionine rather than just read about it. In short: S-Methylmethionine (SMM) is a derivative of methionine with the chemical formula (CH3)2S+CH2CH2CH(NH3+)CO2−. This cation is a naturally-occurring intermediate in many biosynthetic pathways owing to the sulfonium functional group.

Key takeaways

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

Reference excerpt

S-Methylmethionine (SMM) is a derivative of methionine with the chemical formula (CH3)2S+CH2CH2CH(NH3+)CO2−. This cation is a naturally-occurring intermediate in many biosynthetic pathways owing to the sulfonium functional group. It is biosynthesized from L-methionine and S-adenosylmethionine by the enzyme methionine S-methyltransferase. S-methylmethionine is particularly abundant in plants, being more abundant than methionine. S-Methylmethionine is sometimes referred to as vitamin U, but it is not considered a true vitamin. The term was coined in 1950 by Garnett Cheney for uncharacterized anti-ulcerogenic factors in raw cabbage juice that may help speed healing of peptic ulcers.

Biosynthesis and biochemical function S-Methylmethionine arises via the methylation of methionine by S-adenosyl methionine (SAM). The coproduct is S-adenosyl homocysteine. The biological roles of S-methylmethionine are not well understood. Speculated roles include methionine storage, use as a methyl donor, regulation of SAM. A few plants use S-methylmethionine as a precursor to the osmolyte dimethylsulfoniopropionate (DMSP). Intermediates include dimethylsulfoniumpropylamine and dimethylsulfoniumpropionaldehyde.

Beer flavor precursor in barley malt S-Methylmethionine is found in barley and is further created during the malting process. SMM can be subsequently converted to dimethyl sulfide (DMS) during the malt kilning process, causing an undesirable flavor. Lightly kilned malts such as pilsner or lager malts retain much of their SMM content while higher kilned malt such as pale ale malt has substantially more of the SMM converted to DMS in the malt. Darker kilned malts such as Munich malt have virtually no SMM content since most has been converted to DMS. Other crystal malts and roasted malts have no SMM content and often no DMS content since the kilning also drives that compound out of the malt.

References

External links Vitamin U at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

Illustrations

Worked examples

Example 1 — a first encounter with S-Methylmethionine

Start with the simplest possible case. Write down what S-Methylmethionine claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, 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 S-Methylmethionine 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 S-Methylmethionine 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 S-Methylmethionine

In research: S-Methylmethionine appears in chemistry 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 S-Methylmethionine 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: S-Methylmethionine is common in secondary-school and first-year university syllabi. It links to neighbouring topics Alpha-Amino acids, Methylation, Sulfonium compounds, so understanding it makes those chapters shorter.
In everyday life: Look for S-Methylmethionine 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.

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How to study S-Methylmethionine in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what S-Methylmethionine 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 S-Methylmethionine out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is S-Methylmethionine in simple terms?

Why does S-Methylmethionine matter?

Because it connects several chemistry 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 S-Methylmethionine?

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 S-Methylmethionine.