S-Methylmethionine

S-Methylmethionine[1]
IUPAC name (3-Amino-3-carboxy-propyl)-dimethyl-sulfonium
Other names S-Methyl-L-methionine Vitamin U
Identifiers
CAS number	4727-40-6
PubChem	458
Jmol-3D images	Image 1
SMILES C[S+](C)CCC(C(=O)O)N
Properties
Molecular formula	C6H15NO2S+
Molar mass	164.247 g/mol
Melting point	139 °C (282 °F)[1] (bromide salt, decomp.) 134 °C (273 °F)[1] (chloride salt, decomp.)
Hazards
LD50	2760 mg/kg (iv, mice, chloride salt)[1]
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

S-Methylmethionine is a derivative of methionine with chemical formula [(CH₃)₃S(CH₂)₂CHNH₃CO₂]⁺. 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.^[2]

Biochemical function

In the radical-SAM enzymes, an iron-sulfur cluster binds and reduces S-adenosylmethionine to generate a methyl radical, which is involved in many hundreds of biosynthetic transformations.^[3]

The osmolyte dimethylsulfoniopropionate (DMSP), produced by marine algae, is biosynthesized from S-methylmethionine. Intermediates include dimethylsulfoniumpropylamine and dimethylsulfoniumpropionaldehyde.^[4]

"Vitamin U" story

In 1949, cabbage juice was found to significantly increase the rate of healing in patients with gastrointestinal ulceration.^[5] Further work showed that these results are attributed to an unknown, heat-sensitive substance, dubbed the unidentified substance(s) responsible for the rapid healing "vitamin U", although this it is not recognized as a vitamin. S-Methylmethionine is sometimes still referred to as vitamin U in naturopathic medicine, but it is not recognized as a vitamin by mainstream nutrition science.

References

1. ^ ^{a b c d} Merck Index, 12th Edition, 10165
2. ^ 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. 
3. ^ Susan C. Wang and Perry A. Frey (2007). "S-adenosylmethionine as an oxidant: the radical SAM superfamily". Trends in Biochemical Sciences 32 (3): 101–10. doi:10.1016/j.tibs.2007.01.002. PMID 17291766. 
4. ^ McNeil, S. D. (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. 
5. ^ Cheney G (1949). "Rapid healing of peptic ulcers in patients receiving fresh cabbage juice". California Medicine 70 (10). 

Publications related to the "vitamin U" story, especially early history

• Cheney G (1954). "Vitamin U concentrate therapy of peptic ulcer". American Journal of Gastroenterology 21 (3): 230–250. PMID 13138563. .
• Cheney G (1955). "The medical management of gastric ulcers with vitamin U therapy". Stanford Med Bull 13 (2): 204–214. PMID 14386172. .
• Cheney G, Waxler SH, Miller IJ (1956). "Vitamin U therapy of peptic ulcer; experience at San Quentin Prison". Calif Med 84 (1): 39–42. PMC 1532869. PMID 13276831. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1532869. .
• Cheney G (1955). "The medical management of gastric ulcers with vitamin U therapy". Stanford Med Bull 13 (2): 204–214. PMID 14386172. .
• Cheney G (1950). "The nature of the antipepticulcer dietary factor". Stanford Med Bull 8 (3): 144–161. PMID 14782068. 
• Cheney G (1950). "Antipeptic ulcer dietary factor". American Dietetic Association 26 (9). 
• Cheney G (1952). "Vitamin U Therapy of Peptic Ulcer". California Medicine 77 (4): 248–252. PMC 1521464. PMID 13009468. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1521464. 
• STREHLER E (1958). "Contribution to the knowledge of the ulcer-preventive factor (so-called vitamin U) intestinal activity of vitamin U-containing dry extracts of cabbage. II". Hippokrates 29 (19): 629–633. PMID 13610295. 
• Trusov VV, Oreshkov TM (1974). "Therapeutic effect of MMSC1 (vitamin U) on gastric and intestinal function in the treatment of patients with chronic gastritis". Sovetskaia meditsina 8 (0): 121–124. PMID 4428258. 
• Roediger WE, Babidge W, Millard S. (1996). "Methionine derivatives diminish sulphide damage to colonocytes--implications for ulcerative colitis". Gut 39 (1): 77–81. doi:10.1136/gut.39.1.77. PMC 1383236. PMID 8881814. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1383236.