S-Methylmethionine
Encyclopedia
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.
binds and reduces S-adenosylmethionine to generate a methyl radical
, which is involved in many hundreds of biosynthetic transformations.
The osmolyte
dimethylsulfoniopropionate
(DMSP), produced by marine algae
, is biosynthesized from S-methylmethionine. Intermediates include dimethylsulfoniumpropylamine and dimethylsulfoniumpropionaldehyde.
, but it is not recognized as a vitamin
by mainstream nutrition
science.
Methionine
Methionine is an α-amino acid with the chemical formula HO2CCHCH2CH2SCH3. This essential amino acid is classified as nonpolar. This amino-acid is coded by the codon AUG, also known as the initiation codon, since it indicates mRNA's coding region where translation into protein...
with chemical formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
[(CH3)3S(CH2)2CHNH3CO2]+. This cation is an intermediate in many biosynthetic pathways owing to the sulfonium
Sulfonium
A sulfonium ion, also known as sulphonium ion or sulfanium ion, is a positively charged ion featuring three organic substituents attached to sulfur. They have the formula [SR3]+...
functional group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
. 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
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
methionine S-methyltransferase
Methionine S-methyltransferase
In enzymology, a methionine S-methyltransferase is an enzyme that catalyzes the chemical reactionThus, the two substrates of this enzyme are S-adenosyl methionine and L-methionine, whereas its two products are S-adenosylhomocysteine and S-methyl-L-methionine.This enzyme belongs to the family of...
. S-Methylmethionine is particularly abundant in plants, being more abundant than methionine.
Biochemical function
In the radical-SAM enzymes, an iron-sulfur clusterIron-sulfur cluster
For biological Fe-S clusters, see iron-sulfur proteins.Iron-sulfur clusters are ensembles of iron and sulfide centres. Fe-S clusters are most often discussed in the context of the biological role for iron-sulfur proteins. Many Fe-S clusters are known in the area of organometallic chemistry and as...
binds and reduces S-adenosylmethionine to generate a methyl radical
Methyl radical
Methyl radical is a trivalent radical derived from methane, produced by the ultraviolet disassociation of halomethanes....
, which is involved in many hundreds of biosynthetic transformations.
The osmolyte
Osmolyte
Osmolytes are compounds affecting osmosis. They are soluble in the solution within a cell, or in the surrounding fluid, e.g. as plasma osmolytes. They play a role in maintaining cell volume and fluid balance. For example, when a cell swells due to external osmotic pressure, membrane channels open...
dimethylsulfoniopropionate
Dimethylsulfoniopropionate
Dimethylsulfoniopropionate , is an organosulfur compound with the formula 2S+CH2CH2COO−. This zwitterionic metabolite found in marine phytoplankton, seaweeds, and some species of terrestrial and aquatic vascular plants...
(DMSP), produced by marine algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, is biosynthesized from S-methylmethionine. Intermediates include dimethylsulfoniumpropylamine and dimethylsulfoniumpropionaldehyde.
"Vitamin U" story
In 1949, cabbage juice was found to significantly increase the rate of healing in patients with gastrointestinal ulceration. 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 medicineNaturopathic medicine
Naturopathy, or Naturopathic Medicine, is a form of alternative medicine based on a belief in vitalism, which posits that a special energy called vital energy or vital force guides bodily processes such as metabolism, reproduction, growth, and adaptation...
, but it is not recognized as a vitamin
Vitamin
A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on...
by mainstream nutrition
Nutrition
Nutrition is the provision, to cells and organisms, of the materials necessary to support life. Many common health problems can be prevented or alleviated with a healthy diet....
science.