Methionine
Encyclopedia
Methionine
is an α-amino acid
with the chemical formula
HO2CCH(NH2)CH2CH2SCH3. 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 begins.
, methionine is one of two sulfur
-containing proteinogenic amino acids. Its derivative S-adenosyl methionine
(SAM) serves as a methyl donor. Methionine is an intermediate in the biosynthesis of cysteine
, carnitine
, taurine, lecithin
, phosphatidylcholine
, and other phospholipid
s. Improper conversion of methionine can lead to atherosclerosis
.
This amino acid
is also used by plants for synthesis of ethylene
. The process is known as the Yang
Cycle or the methionine cycle.
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 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 protein
s in eukaryote
s and archaea
during translation, although it is usually removed by post-translational modification. In bacteria
, the derivative N-formylmethionine
is used as the initial amino acid.
Rats fed a diet without methionine developed steatohepatitis
. Administration of methionine ameliorated the pathological consequences of methionine deprivation.
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.
Enzymes involved in methionine biosynthesis:
Although mammals cannot synthesize methionine, they can still use it in a variety of biochemical pathways:
.
SAM serves as a methyl-donor in many (2) methyltransferase
reactions, and is converted to S-adenosylhomocysteine (SAH).
(3) Adenosylhomocysteinase
converts SAH to homocysteine
.
There are two fates of homocysteine
: it can be used to regenerate methionine, or to form cysteine.
as a cofactor
.
Homocysteine can also be remethylated using glycine betaine (NNN-trimethyl glycine, TMG) 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 synthase.
methionine can be synthesized from diethyl sodium phthalimidomalonate by alkylation with chloroethylmethylsulfide (ClCH2CH2SCH3) followed by hydrolysis and decarboxylation.
High levels of methionine can be found in sesame seeds, Brazil nuts, fish, meats and some other plant seeds; methionine is also found in cereal
grains. Most fruits and vegetables contain very little of it. Most legumes are also low in methionine. The complement of cereal
(methionine) and legumes (lysine
), providing a complete protein
, is a classic combination, found throughout the world, such as in rice and beans
or tortilla
and beans.
Racemic methionine is sometimes added as an ingredient to pet food
s.
A 2005 study showed methionine restriction without energy restriction extends mouse lifespan.
On the other hand, a study published in Nature
showed adding just the essential amino acid methionine to the diet of fruit flies under dietary restriction (DR - including restriction of essential amino acids) restored fecundity without reducing the lifespans that are typical of DR. Restored to normal levels, "Methionine alone increased fecundity
as much as full feeding, but without reducing lifespan."
Methionine is allowed as a supplement to organic poultry feed under the US certified organic program.
is an α-amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
with the 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....
HO2CCH(NH2)CH2CH2SCH3. This essential amino acid
Essential amino acid
An essential amino acid or indispensable amino acid is an amino acid that cannot be synthesized de novo by the organism , and therefore must be supplied in the diet.-Essentiality vs. conditional essentiality in humans:...
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 begins.
Function
Together with cysteineCysteine
Cysteine is an α-amino acid with the chemical formula HO2CCHCH2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is polar and thus cysteine is usually classified as a hydrophilic amino acid...
, methionine is one of two sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
-containing proteinogenic amino acids. Its derivative S-adenosyl methionine
S-Adenosyl methionine
S-Adenosyl methionine is a common cosubstrate involved in methyl group transfers. SAM was first discovered in Italy by G. L. Cantoni in 1952. It is made from adenosine triphosphate and methionine by methionine adenosyltransferase . Transmethylation, transsulfuration, and aminopropylation are the...
(SAM) serves as a methyl donor. Methionine is an intermediate in the biosynthesis of cysteine
Cysteine
Cysteine is an α-amino acid with the chemical formula HO2CCHCH2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is polar and thus cysteine is usually classified as a hydrophilic amino acid...
, carnitine
Carnitine
Carnitine is a quaternary ammonium compound biosynthesized from the amino acids lysine and methionine. In living cells, it is required for the transport of fatty acids from the cytosol into the mitochondria during the breakdown of lipids for the generation of metabolic energy. It is widely...
, taurine, lecithin
Lecithin
Lecithin is a generic term to designate any group of yellow-brownish fatty substances occurring in animal and plant tissues, and in egg yolk, composed of phosphoric acid, choline, fatty acids, glycerol, glycolipids, triglycerides, and phospholipids .The word lecithin was originally coined in 1847 by...
, phosphatidylcholine
Phosphatidylcholine
Phosphatidylcholines are a class of phospholipids that incorporate choline as a headgroup.They are a major component of biological membranes and can be easily obtained from a variety of readily available sources such as egg yolk or soy beans from which they are mechanically extracted or chemically...
, and other phospholipid
Phospholipid
Phospholipids are a class of lipids that are a major component of all cell membranes as they can form lipid bilayers. Most phospholipids contain a diglyceride, a phosphate group, and a simple organic molecule such as choline; one exception to this rule is sphingomyelin, which is derived from...
s. Improper conversion of methionine can lead to atherosclerosis
Atherosclerosis
Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...
.
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
is also used by plants for synthesis of ethylene
Ethylene
Ethylene is a gaseous organic compound with the formula . It is the simplest alkene . Because it contains a carbon-carbon double bond, ethylene is classified as an unsaturated hydrocarbon. Ethylene is widely used in industry and is also a plant hormone...
. The process is known as the Yang
Shang Fa Yang
Shang Fa Yang was an acclaimed plant scientist and a professor at the University of California, Davis.- Birth and education :Shang Fa Yang was born in 1932 in Taiwan. He earned his bachelor's and master's degrees in agricultural chemistry at the National Taiwan University...
Cycle or the methionine cycle.
Methionine is one of only two amino acids encoded by a single codon (AUG) in the standard genetic code
Genetic code
The genetic code is the set of rules by which information encoded in genetic material is translated into proteins by living cells....
(tryptophan
Tryptophan
Tryptophan is one of the 20 standard amino acids, as well as an essential amino acid in the human diet. It is encoded in the standard genetic code as the codon UGG...
, encoded by UGG, is the other). The codon AUG is also the "Start" message for a ribosome
Ribosome
A ribosome is a component of cells that assembles the twenty specific amino acid molecules to form the particular protein molecule determined by the nucleotide sequence of an RNA molecule....
that signals the initiation of protein translation from mRNA. As a consequence, methionine is incorporated into the N-terminal position of all protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s in eukaryote
Eukaryote
A eukaryote is an organism whose cells contain complex structures enclosed within membranes. Eukaryotes may more formally be referred to as the taxon Eukarya or Eukaryota. The defining membrane-bound structure that sets eukaryotic cells apart from prokaryotic cells is the nucleus, or nuclear...
s and archaea
Archaea
The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon...
during translation, although it is usually removed by post-translational modification. In bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, the derivative N-formylmethionine
N-Formylmethionine
N-Formylmethionine is a proteinogenic amino acid found in Bacteria and related Prokaryotic organelles. It is a derivative of the amino acid methionine in which a formyl group has been added to the amino group...
is used as the initial amino acid.
Rats fed a diet without methionine developed steatohepatitis
Steatohepatitis
Steatohepatitis is a type of liver disease, characterized by inflammation of the liver with concurrent fat accumulation in liver...
. Administration of methionine ameliorated the pathological consequences of methionine deprivation.
Betaines
Biosynthesis
As an essential amino acid, methionine is not synthesized de novoDe novo synthesis
De novo synthesis refers to the synthesis of complex molecules from simple molecules such as sugars or amino acids, as opposed to their being recycled after partial degradation. For example, nucleotides are not needed in the diet as they can be constructed from small precursor molecules such as...
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
Aspartic acid
Aspartic acid is an α-amino acid with the chemical formula HOOCCHCH2COOH. The carboxylate anion, salt, or ester of aspartic acid is known as aspartate. The L-isomer of aspartate is one of the 20 proteinogenic amino acids, i.e., the building blocks of proteins...
and cysteine
Cysteine
Cysteine is an α-amino acid with the chemical formula HO2CCHCH2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is polar and thus cysteine is usually classified as a hydrophilic amino acid...
. First, aspartic acid
Aspartic acid
Aspartic acid is an α-amino acid with the chemical formula HOOCCHCH2COOH. The carboxylate anion, salt, or ester of aspartic acid is known as aspartate. The L-isomer of aspartate is one of the 20 proteinogenic amino acids, i.e., the building blocks of proteins...
is converted via β-aspartyl-semialdehyde into homoserine, introducing the pair of contiguous methylene groups. Homoserine converts to O-succinyl homoserine
Homoserine
Homoserine is an α-amino acid with the chemical formula HO2CCHCH2CH2OH. L-Homoserine is not one of the common amino acids encoded by DNA. It differs from the proteinogenic amino acid serine by insertion of an additional methylene group...
, which then reacts with cysteine to produce cystathionine
Cystathionine
Cystathionine is an intermediate in the synthesis of cysteine.It is generated from homocysteine and serine by cystathionine beta synthase.It is cleaved into cysteine and α-ketobutyrate by cystathionine gamma-lyase....
, which is cleaved to yield homocysteine
Homocysteine
Homocysteine is a non-protein amino acid with the formula HSCH2CH2CHCO2H. It is a homologue of the amino acid cysteine, differing by an additional methylene group. It is biosynthesized from methionine by the removal of its terminal Cε methyl group...
. Subsequent methylation of the thiol
Thiol
In organic chemistry, a thiol is an organosulfur compound that contains a carbon-bonded sulfhydryl group...
group by folates
Folic acid
Folic acid and folate , as well as pteroyl-L-glutamic acid, pteroyl-L-glutamate, and pteroylmonoglutamic acid are forms of the water-soluble vitamin B9...
affords methionine. Both cystathionine-γ-synthase and cystathionine-β-lyase require pyridoxyl-5'-phosphate
Pyridoxal-phosphate
Pyridoxal-phosphate is a prosthetic group of some enzymes. It is the active form of vitamin B6, which comprises three natural organic compounds, pyridoxal, pyridoxamine and pyridoxine.-Role as a coenzyme:...
as a cofactor
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....
, whereas homocysteine methyltransferase requires vitamin B12
Vitamin B12
Vitamin B12, vitamin B12 or vitamin B-12, also called cobalamin, is a water-soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins...
as a cofactor.
Enzymes involved in methionine biosynthesis:
- aspartokinaseAspartokinaseAspartokinase is an enzyme that catalyzes the phosphorylation of the amino acid aspartate. This reaction is the first step in the biosynthesis of three essential amino acids: methionine, lysine, and threonine, known as the "aspartate family"...
- β-aspartate semialdehyde dehydrogenaseDehydrogenaseA dehydrogenase is an enzyme that oxidises a substrate by a reduction reaction that transfers one or more hydrides to an electron acceptor, usually NAD+/NADP+ or a flavin coenzyme such as FAD or FMN.-Examples:...
- homoserine dehydrogenase
- homoserine O-transsuccinylase
- cystathionine-γ-synthaseSynthaseIn biochemistry, a synthase is an enzyme that catalyses a synthesis process.Following the EC number classification, they belong to the group of ligases, with lyases catalysing the reverse reaction....
- cystathionine-β-lyaseLyaseIn biochemistry, a lyase is an enzyme that catalyzes the breaking of various chemical bonds by means other than hydrolysis and oxidation, often forming a new double bond or a new ring structure...
- methionine synthase (in mammals, this step is performed by homocysteine methyltransferase)
Other biochemical pathways
Generation of homocysteine
Methionine is converted to S-adenosylmethionine (SAM) by (1) methionine adenosyltransferaseMethionine adenosyltransferase
Methionine adenosyltransferase is an enzyme which catalyses the synthesis of S-adenosylmethionine from methionine and ATP.-External links:...
.
SAM serves as a methyl-donor in many (2) methyltransferase
Methyltransferase
A methyltransferase is a type of transferase enzyme that transfers a methyl group from a donor to an acceptor.Methylation often occurs on nucleic bases in DNA or amino acids in protein structures...
reactions, and is converted to S-adenosylhomocysteine (SAH).
(3) Adenosylhomocysteinase
Adenosylhomocysteinase
Adenosylhomocysteinase is an enzyme that converts S-adenosylhomocysteine to homocysteine and adenosine....
converts SAH to homocysteine
Homocysteine
Homocysteine is a non-protein amino acid with the formula HSCH2CH2CHCO2H. It is a homologue of the amino acid cysteine, differing by an additional methylene group. It is biosynthesized from methionine by the removal of its terminal Cε methyl group...
.
There are two fates of homocysteine
Homocysteine
Homocysteine is a non-protein amino acid with the formula HSCH2CH2CHCO2H. It is a homologue of the amino acid cysteine, differing by an additional methylene group. It is biosynthesized from methionine by the removal of its terminal Cε methyl group...
: it can be used to regenerate methionine, or to form cysteine.
Regeneration of methionine
Methionine can be regenerated from homocysteine via (4) methionine synthase in a reaction that requires Vitamin B12Vitamin B12
Vitamin B12, vitamin B12 or vitamin B-12, also called cobalamin, is a water-soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins...
as a cofactor
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....
.
Homocysteine can also be remethylated using glycine betaine (NNN-trimethyl glycine, TMG) 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 synthase.
Conversion to cysteine
Homocysteine can be converted to cysteine.- (5) Cystathionine-β-synthase (a PLP-dependent enzyme) combines homocysteine and serine to produce cystathionineCystathionineCystathionine is an intermediate in the synthesis of cysteine.It is generated from homocysteine and serine by cystathionine beta synthase.It is cleaved into cysteine and α-ketobutyrate by cystathionine gamma-lyase....
. Instead of degrading cystathionineCystathionineCystathionine is an intermediate in the synthesis of cysteine.It is generated from homocysteine and serine by cystathionine beta synthase.It is cleaved into cysteine and α-ketobutyrate by cystathionine gamma-lyase....
via cystathionine-β-lyase, as in the biosynthetic pathway, cystathionine is broken down to cysteineCysteineCysteine is an α-amino acid with the chemical formula HO2CCHCH2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is polar and thus cysteine is usually classified as a hydrophilic amino acid...
and α-ketobutyrate via (6) cystathionine-γ-lyase. - (7) The enzyme α-ketoacid dehydrogenase converts α-ketobutyrate to propionyl-CoAPropionyl-CoAPropionyl-CoA is a coenzyme A derivative of propionic acid.-Production:There are several different ways in which it is formed:* It is formed as a product of beta-oxidation of odd-chain fatty acids....
, which is metabolized to succinyl-CoASuccinyl-CoASuccinyl-Coenzyme A, abbreviated as Succinyl-CoA or SucCoA, is a combination of succinic acid and coenzyme A.-Source:It is an important intermediate in the citric acid cycle, where it is synthesized from α-Ketoglutarate by α-ketoglutarate dehydrogenase through decarboxylation...
in a three-step process (see propionyl-CoAPropionyl-CoAPropionyl-CoA is a coenzyme A derivative of propionic acid.-Production:There are several different ways in which it is formed:* It is formed as a product of beta-oxidation of odd-chain fatty acids....
for pathway).
Synthesis
RacemicRacemic
In chemistry, a racemic mixture, or racemate , is one that has equal amounts of left- and right-handed enantiomers of a chiral molecule. The first known racemic mixture was "racemic acid", which Louis Pasteur found to be a mixture of the two enantiomeric isomers of tartaric acid.- Nomenclature :A...
methionine can be synthesized from diethyl sodium phthalimidomalonate by alkylation with chloroethylmethylsulfide (ClCH2CH2SCH3) followed by hydrolysis and decarboxylation.
Dietary sources
| Food | g/100g |
|---|---|
| Egg Egg -Biology/food:*Egg , an organic vessel in which an embryo first begins to develop*Ovum, a female egg cell*Egg , the egg of a fowl or fish consumed as food-Places:*Egg Island *Egg, Switzerland, a Swiss municipality... , white, dried, powder, glucose reduced |
3.204 |
| Sesame seeds flour (low fat) | 1.656 |
| Brazil nut Brazil Nut The Brazil nut is a South American tree in the family Lecythidaceae, and also the name of the tree's commercially harvested edible seed.- Order :... s |
1.008 |
| Soy protein concentrate | 0.814 |
| Chicken Chicken The chicken is a domesticated fowl, a subspecies of the Red Junglefowl. As one of the most common and widespread domestic animals, and with a population of more than 24 billion in 2003, there are more chickens in the world than any other species of bird... , broilers or fryers, roasted |
0.801 |
| Fish Fish Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups... , tuna, light, canned in water, drained solids |
0.755 |
| Wheat germ | 0.456 |
| Oat Oat The common oat is a species of cereal grain grown for its seed, which is known by the same name . While oats are suitable for human consumption as oatmeal and rolled oats, one of the most common uses is as livestock feed... |
0.312 |
| Peanut Peanut The peanut, or groundnut , is a species in the legume or "bean" family , so it is not a nut. The peanut was probably first cultivated in the valleys of Peru. It is an annual herbaceous plant growing tall... s |
0.309 |
| Chickpea Chickpea The chickpea is a legume of the family Fabaceae, subfamily Faboideae... |
0.253 |
| Corn Maize Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable... , yellow |
0.197 |
| Almonds | 0.151 |
| Beans, pinto, cooked | 0.117 |
| Lentils, cooked | 0.077 |
| Rice Rice Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies... , brown, medium-grain, cooked |
0.052 |
High levels of methionine can be found in sesame seeds, Brazil nuts, fish, meats and some other plant seeds; methionine is also found in cereal
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...
grains. Most fruits and vegetables contain very little of it. Most legumes are also low in methionine. The complement of cereal
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...
(methionine) and legumes (lysine
Lysine
Lysine is an α-amino acid with the chemical formula HO2CCH4NH2. It is an essential amino acid, which means that the human body cannot synthesize it. Its codons are AAA and AAG....
), providing a complete protein
Complete protein
A complete protein is a source of protein that contains an adequate proportion of all nine of the essential amino acids necessary for the dietary needs of humans or other animals...
, is a classic combination, found throughout the world, such as in rice and beans
Rice and beans
Rice and beans is a very popular dish in Latin America, the Caribbean, and in communities of Latino, Caribbean or Sephardic...
or tortilla
Tortilla
In Mexico and Central America, a tortilla is a type of thin, unleavened flat bread, made from finely ground maize...
and beans.
Racemic methionine is sometimes added as an ingredient to pet food
Pet food
Pet food is plant or animal material intended for consumption by pets. Typically sold in pet stores and supermarkets, it is usually specific to the type of animal, such as dog food or cat food...
s.
Methionine restriction
There is some evidence that restricting methionine consumption can increase lifespans in some animals.A 2005 study showed methionine restriction without energy restriction extends mouse lifespan.
On the other hand, a study published in Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
showed adding just the essential amino acid methionine to the diet of fruit flies under dietary restriction (DR - including restriction of essential amino acids) restored fecundity without reducing the lifespans that are typical of DR. Restored to normal levels, "Methionine alone increased fecundity
Fecundity
Fecundity, derived from the word fecund, generally refers to the ability to reproduce. In demography, fecundity is the potential reproductive capacity of an individual or population. In biology, the definition is more equivalent to fertility, or the actual reproductive rate of an organism or...
as much as full feeding, but without reducing lifespan."
Other uses
DL-methionine is sometimes given as a supplement to dogs; it helps keep dogs from damaging grass by reducing the pH of the urine.Methionine is allowed as a supplement to organic poultry feed under the US certified organic program.
See also
- AllantoinAllantoinAllantoin is a chemical compound with formula C4H6N4O3. It is also called 5-ureidohydantoin or glyoxyldiureide. It is a diureide of glyoxylic acid....
- Formylmethionine
- Methionine oxidationMethionine oxidationMethionine oxidation is the oxidation of the sulfur of the amino acid methionine resulting in methionine sulfoxide or methionine sulfone. The sulfur-containing amino acids methionine and cysteine are more easily oxidized than the other amino acids...
- Paracetamol poisoning - A Methionine-Paracetamol preparation that might prevent hepatotoxicity.
- Photo-reactive methioninePhoto-reactive amino acid analogPhoto-reactive amino acid analogs for in-vivo crosslinking of protein complexes were introduced in 2005 by researchers from the Max Planck Institute. In this method, cells are grown with photoreactive diazirine analogs to leucine and methionine, which are incorporated into proteins...