Showing metabocard for L-Methionine (MMDBc0000140)

Record Information
Version1.0
StatusDetected and Quantified
Creation Date2020-10-27 23:37:20 UTC
Update Date2022-08-30 23:58:48 UTC
MiMeDB IDMMDBc0000140
Metabolite Identification
Common NameL-Methionine
DescriptionMethionine is an essential amino acid (there are 9 essential amino acids) required for normal growth and development of humans, other mammals, and avian species. In addition to being a substrate for protein synthesis, it is an intermediate in transmethylation reactions, serving as the major methyl group donor in vivo, including the methyl groups for DNA and RNA intermediates. Methionine is a methyl acceptor for 5-methyltetrahydrofolate-homocysteine methyltransferase (methionine synthase), the only reaction that allows for the recycling of this form of folate, and is also a methyl acceptor for the catabolism of betaine. Methionine is the metabolic precursor for cysteine. Only the sulfur atom from methionine is transferred to cysteine; the carbon skeleton of cysteine is donated by serine (PMID: 16702340 ). There is a general consensus concerning normal sulfur amino acid (SAA) requirements. WHO recommendations amount to 13 mg/kg per 24 h in healthy adults. This amount is roughly doubled in artificial nutrition regimens. In disease or after trauma, requirements may be altered for methionine, cysteine, and taurine. Although in specific cases of congenital enzyme deficiency, prematurity, or diminished liver function, hypermethioninemia or hyperhomocysteinemia may occur, SAA supplementation can be considered safe in amounts exceeding 2-3 times the minimum recommended daily intake. Apart from some very specific indications (e.g. acetaminophen poisoning) the usefulness of SAA supplementation is not yet established (PMID: 16702341 ). Methionine is known to exacerbate psychopathological symptoms in schizophrenic patients, but there is no evidence of similar effects in healthy subjects. The role of methionine as a precursor of homocysteine is the most notable cause for concern. Acute doses of methionine can lead to acute increases in plasma homocysteine, which can be used as an index of the susceptibility to cardiovascular disease. Sufficiently high doses of methionine can actually result in death. Longer-term studies in adults have indicated no adverse consequences of moderate fluctuations in dietary methionine intake, but intakes higher than 5 times the normal amount resulted in elevated homocysteine levels. These effects of methionine on homocysteine and vascular function are moderated by supplements of vitamins B-6, B-12, C, and folic acid (PMID: 16702346 ). When present in sufficiently high levels, methionine can act as an atherogen and a metabotoxin. An atherogen is a compound that when present at chronically high levels causes atherosclerosis and cardiovascular disease. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of methionine are associated with at least ten inborn errors of metabolism, including cystathionine beta-synthase deficiency, glycine N-methyltransferase deficiency, homocystinuria, tyrosinemia, galactosemia, homocystinuria-megaloblastic anemia due to defects in cobalamin metabolism, methionine adenosyltransferase deficiency, methylenetetrahydrofolate reductase deficiency, and S-adenosylhomocysteine (SAH) hydrolase deficiency. Chronically elevated levels of methionine in infants can lead to intellectual disability and other neurological problems, delays in motor skills, sluggishness, muscle weakness, and liver problems. Many individuals with these metabolic disorders tend to develop cardiovascular disease later in life. Studies on feeding rodents high levels of methionine have shown that methionine promotes atherosclerotic plaques independently of homocysteine levels (PMID: 26647293 ). A similar study in Finnish men showed the same effect (PMID: 16487911 ).
Structure
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MOL for #<Metabolite:0x0000564abeec1968>

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SynonymsNot Available
Chemical FormulaC5H11NO2S
Average Molecular Weight149.211
Monoisotopic Molecular Weight149.051049291
IUPAC NameNot Available
Traditional NameNot Available
CAS Registry Number63-68-3
SMILESNot Available
InChI Identifier
InChI=1S/C5H11NO2S/c1-9-3-2-4(6)5(7)8/h4H,2-3,6H2,1H3,(H,7,8)/t4-/m0/s1
InChI KeyFFEARJCKVFRZRR-BYPYZUCNSA-N