Methionine
IUPAC name	(S)-2-amino-4-(methylsulfanyl)-butanoic acid
Other names	Met, M
Identifiers
CAS number	63-68-3
PubChem	876
EINECS number	200-562-9
SMILES	CSCC[C@H](N)C(O)=O
Properties
Molecular formula	C5H11NO2S
Molar mass	149.21 g/mol
Density	1.340 g cm-3
Melting point	281 °C Image File history File links Size of this preview: 800 × 489 pixelsFull resolution (1100 × 672 pixel, file size: 30 KB, MIME type: image/png) File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Size of this preview: 800 × 454 pixelsFull resolution (1100 × 624 pixel, file size: 138 KB, MIME type: image/png) File historyClick on a date/time to view the file as it appeared at that time. ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... PubChem is a database of chemical molecules. ... The EINECS number (for European Inventory of Existing Chemical Substances) is a registry number given to each chemical substance commercially available in the European Union between 1 January 1971 and 18 September 1981. ... The simplified molecular input line entry specification or SMILES is a specification for unambiguously describing the structure of chemical molecules using short ASCII strings. ... A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... This article does not cite any references or sources. ... For other uses, see Density (disambiguation). ... The melting point of a crystalline solid is the temperature range at which it changes state from solid to liquid. ...
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Methionine is an α-amino acid with the chemical formula HO₂CCH(NH₂)CH₂CH₂SCH₃. This essential amino acid is classified as nonpolar. Together with cysteine, methionine is one of two sulfur-containing proteinogenic amino acids. Its derivative S-adenosyl methionine (SAM) serves as a methyl donor. Methionine in an intermediate in the biosynthesis of cysteine, carnitine, and taurine, lecithin, phosphatidylcholine, and other phospholipids. Improper conversion of methionine can lead to atherosclerosis. Physical properties Hazard properties Chemical properties Pharmacological properties OrganicBox_complete a  63-68-3 EINECS for L-Methionine a  PubChem 876 a  PubChem 6137 Category: ... Physical properties Hazard properties Chemical properties Pharmacological properties OrganicBox_complete a  63-68-3 EINECS for L-Methionine a  PubChem 876 a  PubChem 6137 Category: ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... The relative dielectric constant of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux. ... Physical properties Hazard properties Chemical properties Pharmacological properties OrganicBox_complete a  63-68-3 EINECS for L-Methionine a  PubChem 876 a  PubChem 6137 Category: ... Physical properties Hazard properties Chemical properties Pharmacological properties OrganicBox_complete a  63-68-3 EINECS for L-Methionine a  PubChem 876 a  PubChem 6137 Category: ... Ultraviolet-Visible Spectroscopy or Ultraviolet-Visible Spectrophotometry (UV/ VIS) involves the spectroscopy of photons (spectrophotometry). ... Infrared spectroscopy (IR Spectroscopy) is the subset of spectroscopy that deals with the IR region of the EM spectrum. ... Nuclear magnetic resonance spectroscopy most commonly known as NMR spectroscopy is the name given to the technique which exploits the magnetic properties of certain nuclei. ... Mass spectrometry (also known as mass spectroscopy (deprecated)[1] or informally, mass-spec and MS) is an analytical technique used to measure the mass-to-charge ratio of ions. ... In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals) and 25 degrees Celsius (298. ... Phenylalanine is one of the standard amino acids. ... A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... An essential amino acid or indispensable amino acid is an amino acid that cannot be synthesized de novo by the organism (usually referring to humans), and therefore must be supplied in the diet. ... In chemistry, a nonpolar compound is one that does not have concentrations of positive or negative electric charge. ... Cysteine is a naturally occurring, sulfur-containing amino acid that is found in most proteins, although only in small quantities. ... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16, 3, p Appearance lemon yellow Standard atomic weight 32. ... This article does not cite its references or sources. ... In chemistry a methyl-group is a hydrophobic Alkyl functional group which is derived from methane (CH4). ... This article or section contains information that has not been verified and thus might not be reliable. ... Taurine, or 2-aminoethanesulfonic acid, is an organic acid that is a major constituent of bile, and can be found in lower amounts in the tissues of many animals including humans. ... Lecithin is mostly a mixture of glycolipids, triglycerides, and phospholipids (e. ... Lecithin, also known as Phosphatidylcholine Lecithin is usually used as synonym for phosphatidylcholine, a phospholipid which is the major component of a phosphatide fraction which may be isolated from either egg yolk (in Greek lekithos - λεκιθος), or soy beans. ... Phospholipid Two schematic representations of a phospholipid. ...

Methionine is one of only two amino acids encoded by a single codon (AUG) in the standard genetic code (tryptophan, encoded by UGG, is the other). The codon AUG is also significant, in that it carries the "Start" message for a ribosome that signals the initiation of protein translation from mRNA. As a consequence, methionine is incorporated into the N-terminal position of all proteins in eukaryotes and archaea during translation, although it is usually removed by post-translational modification. For a non-technical introduction to the topic, see Introduction to Genetics. ... Tryptophan is an essential amino acid involved in human nutrition. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... Translation is the second process of protein biosynthesis (part of the overall process of gene expression). ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Chromalveolata Protista Alternative phylogeny Unikonta Opisthokonta Metazoa Choanozoa Eumycota Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (), or archaebacteria, are a major group of microorganisms. ... Posttranslational modification means the chemical modification of a protein after its translation. ...

Biosynthesis

As an essential amino acid, methionine is not synthesized in humans, hence we must ingest methionine or methionine-containing proteins. In plants and microorganisms, methionine is synthesized via a pathway that uses both aspartic acid and cysteine. First, aspartic acid is converted via β-aspartyl-semialdehyde into homoserine, introducing the pair of contiguous methylene groups. Homoserine converts to O-succinyl homoserine, which then reacts with cysteine to produce cystathionine, which is cleaved to yield homocysteine. Subsequent methylation of the thiol group by folates affords methionine. Both cystathionine-γ-synthase and cystathionine-β-lyase require Pyridoxyl-5'-phosphate as a cofactor, whereas homocysteine methyltransferase requires Vitamin B12 as a cofactor.^[1] Aspartic acid (Asp, D), also known as aspartate, the name of its anion, is one of the 20 natural proteinogenic amino acids which are the building blocks of proteins. ... Cysteine is a naturally occurring, sulfur-containing amino acid that is found in most proteins, although only in small quantities. ... Homoserine is a more reactive variant of the amino acid serine. ... Cystathionine is an intermediate in the synthesis of cysteine. ... Homocysteine is a chemical compound with the formula HSCH2CH2CH(NH2)CO2H. It is a homologue of the naturally-occurring amino acid cysteine, differing in that its side-chain contains an additional methylene (-CH2-) group before the thiol (-SH) group. ... Sulphydryl // In organic chemistry, a thiol is a compound that contains the functional group composed of a sulfur atom and a hydrogen atom (-SH). ... Folic acid and folate (the anion form) are forms of the water-soluble Vitamin B9. ... This article does not cite any references or sources. ... Cystathionine-beta-lyase is an enzyme used in the biosynthesis of methionine. ... Pyridoxal-phosphate (PLP, pyridoxal-5-phosphate) is a cofactor of many enzymatic reactions. ... A cofactor is the following: In mathematics a cofactor is the minor of an element of a square matrix. ... Homocysteine methyltransferase is an enzyme which converts homocysteine to methionine. ... Cyanocobalamin is a compound that is metabolized to a vitamin in the B complex commonly known as vitamin B12 (or B12 for short). ...

Enzymes involved in methionine biosynthesis:

1. aspartokinase
2. β-aspartate semialdehyde dehydrogenase
3. homoserine dehydrogenase
4. homoserine acyltransferase
5. cystathionine-γ-synthase
6. cystathionine-β-lyase
7. methionine synthase (in mammals, this step is performed by homocysteine methyltransferase)

Aspartokinase is an enzyme that catalyzes the phosphorylation of the amino acid aspartate. ... A dehydrogenase is an enzyme that oxidizes a substrate by transferring one or more protons and a pair of electrons to an acceptor, usually NAD/NADP or a flavin coenzyme such as FAD or FMN. Common examples of dehydrogenase enzymes in the TCA cycle are pyruvate dehydrogenase, isocitrate dehydrogenase, and... Acetyl Acyltransferase is a type of transferase enzyme which acts upon acyl groups. ... In biochemistry, a synthase is an enzyme which catalyzes a synthesis process. ... In biochemistry, a lyase is an enzyme that breaks various chemical bonds by means other than hydrolysis and oxidation, often forming a new double bond or a new ring structure. ... Catalyses the conversion of homocysteine to methionine using vitamin B12 (cobolamine) as a cofactor. ... Homocysteine methyltransferase is an enzyme which converts homocysteine to methionine. ... Image File history File links Size of this preview: 551 × 599 pixelsFull resolution (769 × 836 pixel, file size: 13 KB, MIME type: image/gif) Created by Inositol using Chemsketch 8. ...

Other biochemical pathways

Although mammals cannot synthesize methionine, they can still utilize it in a variety of biochemical pathways:

Methionine is converted to S-adenosylmethionine (SAM) by (1) methionine adenosyltransferase. SAM serves as a methyl-donor in many (2) methyltransferase reactions and is converted to S-adenosylhomocysteine (SAH). (3) adenosylhomocysteinase converts SAH to homocysteine. It has been suggested that this article or section be merged into S-Adenosyl methionine. ... Methionine adenosyltransferase is an enzyme which methionine to S-adenosylmethionine (SAM). ... Methyltransferase can refer to: DNA methyltransferase Histone methyltransferase Category: ... S-adenosylhomocysteine is an intermediate in the synthesis of cysteine. ... Adenosylhomocysteinase is an enzyme which converts S-adenosylhomocysteine to homocysteine. ... Homocysteine is a chemical compound with the formula HSCH2CH2CH(NH2)CO2H. It is a homologue of the naturally-occurring amino acid cysteine, differing in that its side-chain contains an additional methylene (-CH2-) group before the thiol (-SH) group. ...

There are two fates of homocysteine. Homocysteine is a chemical compound with the formula HSCH2CH2CH(NH2)CO2H. It is a homologue of the naturally-occurring amino acid cysteine, differing in that its side-chain contains an additional methylene (-CH2-) group before the thiol (-SH) group. ...

• First, methionine can be regenerated from homocysteine via (4) methionine synthase. It can also be remethylated using glycine betaine (NNN-trimethyl glycine) to methionine via the enzyme Betaine-homocysteine methyltransferase (E.C.2.1.1.5, BHMT). BHMT makes up to 1.5% of all the soluble protein of the liver, and recent evidence suggests that it may have a greater influence on methionine and homocysteine homeostasis than Methionine sythase.
• Alternatively, homocysteine can be converted to cysteine. (5) cystathionine-β-synthase (a PLP-dependent enzyme) combines homocysteine and serine to produce cystathionine. Instead of degrading cystathionine via cystathionine-β-lyase as in the biosynthetic pathway, cystathionine is broken down to cysteine and α-ketobutyrate via (6) cystathionine-γ-lyase. (7) α-ketoacid dehydrogenase converts α-ketobutyrate to propionyl-CoA, which is metabolized to succinyl-CoA in a three-step process (see propionyl-CoA for pathway).

Catalyses the conversion of homocysteine to methionine using vitamin B12 (cobolamine) as a cofactor. ... Betaine-homocysteine methyltransferase is an enzyme which generates dimethylglycine and methionine. ... Cystathionine β-synthase (CBS) is a multidomainal enzyme with three modules and a heme domain. ... Cystathionine is an intermediate in the synthesis of cysteine. ... Cystathionine is an intermediate in the synthesis of cysteine. ... Cystathionine-beta-lyase is an enzyme used in the biosynthesis of methionine. ... Cysteine is a naturally occurring, sulfur-containing amino acid that is found in most proteins, although only in small quantities. ... Alpha-ketobutyric acid is a product of the lysis of cystathionine. ... Cystathionine gamma-lyase (or cystathionase) is an enzyme which breaks down cystathionine into cysteine and α-ketobutyrate. ... Propionyl-CoA is a coenzyme A derivative of propionic acid. ... Categories: Biochemistry stubs ... Propionyl-CoA is a coenzyme A derivative of propionic acid. ... Image File history File links Size of this preview: 525 × 599 pixelsFull resolution (682 × 778 pixel, file size: 11 KB, MIME type: image/gif) Created by Inositol using Chemsketch 8. ...

Synthesis

Racemic methionine can be synthesized from diethyl sodium phthalimidomalonate by alkylation with chloroethylmethylsulfide (ClCH₂CH₂SCH₃) followed by hydrolysis and decarboxylation.^[2] In chemistry, a racemate is a mixture of equal amounts of left- and right-handed stereoisomers of a chiral molecule. ...

Dietary aspects

High levels of methionine can be found in sesame seeds, Brazil nuts, fish, meats, and some other plant seeds. ^{[citation needed]} Most fruit and vegetables contain very little; however, some have significant amounts, such as spinach, potatoes, and boiled corn.^{[citation needed]} DL-methionine is sometimes added as an ingredient to pet foods.^{[citation needed]} Methionine, cysteine and soy protein heated in a small amount of water creates a meat like aroma. Articles in category Pet foods There are 16 articles in this section of this category. ...

See also

• Allantoin
• Formylmethionine

Allantoin is a botanical extract of the comfrey plant and is used for its healing, soothing, and anti-irritating properties. ... Formylmethionine (fMet) is a modified form of methionine in which a formyl group has been added to methionines amino group. ...

References

1. ^ Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. ISBN 1-57259-153-6.
2. ^ Barger, G.; Weichselbaum, T. E. (1943). "dl-Methionine". Org. Synth.; Coll. Vol. 2: 384.  

Organic Syntheses is a scientific journal that Since 1921 has provided the chemistry community with annual collections of detailed and checked procedures for the organic synthesis of organic compounds. ...

External links

• Foods containing methionine
• Computational Chemistry Wiki