S-Methylmethionine
chemical compound
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).
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Stable identifiers, scientific names and standards terminology offer the best bridge between this overview and specialist evidence. The source revision retrieved here is dated Sep 14, 2026. The linked authority identifier is Q1329492. The Library of Congress control number is sh85144005. 1 of 1 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 1950.
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This entry incorporates text from “S-Methylmethionine” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.