S-Methylmethionine

S-Methylmethionine

Names
IUPAC name (3-Amino-3-carboxy-propyl)-dimethyl-sulfonium
Other names S-Methyl-L-methionine Vitamin U
Identifiers
CAS Number	4727-40-6 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:17728 N
ChemSpider	128519 N
KEGG	C03172 N
PubChem	145692
InChI InChI=1S/C6H13NO2S/c1-10(2)4-3-5(7)6(8)9/h5H,3-4,7H2,1-2H3/p+1/t5-/m0/s1 N Key: YDBYJHTYSHBBAU-YFKPBYRVSA-O N InChI=1/C6H13NO2S/c1-10(2)4-3-5(7)6(8)9/h5H,3-4,7H2,1-2H3/p+1/t5-/m0/s1 Key: YDBYJHTYSHBBAU-YJIVXYNWBY
SMILES C[S+](C)CC[C@@H](C(=O)O)N
Properties
Chemical formula	C6H14NO2S+
Molar mass	164.243 g/mol
Melting point	139 °C (282 °F; 412 K) (bromide salt, decomposes) 134 °C (273 °F) (chloride salt, decomposes)
Hazards
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).
N  (what is YN ?)
Infobox references

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.

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.

S-Methylmethionine is claimed to have protective effects in the gastrointestinal mucosa and in the liver.