|Jmol 3D model||Interactive image|
|Molar mass||164.247 g/mol|
|Melting point||139 °C (282 °F; 412 K) (bromide salt, decomposes)
134 °C (273 °F) (chloride salt, decomposes)
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
|2760 mg/kg (iv, mice, chloride salt)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
S-Methylmethionine (SMM) is a derivative of methionine with the chemical formula (CH3)2S+CH2CH2CH(NH3+)CO2−. This cation is an intermediate in many biosynthetic pathways owing to the sulfonium functional group. The natural derivative S-methylmethionine is biosynthesized from L-methionine which is first converted to S-adenosylmethionine. The subsequent conversion, involving replacement of the adenosyl group by a methyl group is catalyzed 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
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
- Merck Index, 12th ed., 10165 ISBN 0-911910-12-3
- Bourgis F (1999). "S-methylmethionine plays a major role in phloem sulfur transport and is synthesized by a novel type of methyltransferase". The Plant Cell Online. 11 (8): 1485–1498. doi:10.1105/tpc.11.8.1485.
- National Center for Biomedical Ontology. "Methylmethionine Sulfonium Chloride".
- Cheney G (September 1950). "Anti-peptic ulcer dietary factor (vitamin "U") in the treatment of peptic ulcer". J Am Diet Assoc. 26 (9): 668–72. PMID 15436263.
- Patel AD, Prajapati NK (2012). "Review on Biochemical Importance of Vitamin-U" (PDF). Journal of Chemical and Pharmaceutical Research. 4 (1): 209–215.
- McNeil SD (1999). "Betaines and related osmoprotectants. Targets for metabolic engineering of stress resistance". Plant Physiology. 120 (4): 945–949. doi:10.1104/pp.120.4.945.
- Hornsey IS (1999). Brewing. Royal Society of Chemistry. p. 47. ISBN 9780854045686.