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SpeciesSaccharomyces cerevisiae
StrainBaker's yeast
Description2-Oxo-4-methylthiobutanoic acid, also known as 4-(methylsulfanyl)-2-oxobutanoate or 2-keto-4-methylthiobutyrate, belongs to the class of organic compounds known as thia fatty acids. These are fatty acid derivatives obtained by insertion of a sulfur atom at specific positions in the chain. 2-Oxo-4-methylthiobutanoic acid is a very hydrophobic molecule, practically insoluble (in water), and relatively neutral.
  • 2-keto-4-methylthiobutyrate
  • 2-keto-4-methylthiobutyric acid
  • 2-ketomethiobutyrate
  • 2-Oxo-4-methylthiobutanoate
  • 2-oxo-4-methylthiobutanoic acid
  • 4-methylthio-2-ketobutanoate
  • 4-methylthio-2-ketobutyrate
  • 4-methylthio-2-oxobutanoate
  • 4-methylthio-2-oxobutanoic acid
  • 4-methylthio-2-oxobutyrate
  • Butanoic acid, 4-(methylthio)-2-oxo-
  • Butyric acid, 4-(methylthio)-2-oxo-
  • keto-4-methylthiobutyrate
  • ketomethiobutyrate
  • ketomethiobutyric acid
  • KMTB
  • methylthiobutyrate
  • methylthiobutyric acid
  • 2-Oxomethionine
  • 4-(METHYLsulfanyl)-2-oxobutanoIC ACID
  • alpha-oxo-gamma-Methylthiobutyric acid
  • 4-(Methylsulfanyl)-2-oxobutanoate
  • 4-(METHYLsulphanyl)-2-oxobutanoate
  • 4-(METHYLsulphanyl)-2-oxobutanoic acid
  • a-oxo-g-Methylthiobutyrate
  • a-oxo-g-Methylthiobutyric acid
  • alpha-oxo-gamma-Methylthiobutyrate
  • Α-oxo-γ-methylthiobutyrate
  • Α-oxo-γ-methylthiobutyric acid
  • 4-Methylthio-2-ketobutanoic acid
  • alpha-Keto-methiolbutyric acid
  • 2-Keto-4-methylthiobutanoic acid
  • 2-Keto-4-thiomethylbutyrate
  • 2-oxo-4-Thiomethylbutyric acid
  • alpha-Keto-gamma-methiolbutyrate
  • alpha-Ketomethionine
  • alpha-Oxomethionine
  • 2-Keto-4-methylthiobutyric acid, monosodium salt
  • 2-Ketothiomethylbutyric acid
  • 4-Methylthio-2-oxobutyric acid
  • S-Methyl-alpha-ketobutyric acid
  • 2-Keto-4-methylthiobutyric acid, calcium salt
  • 4-Methylthio-2-ketobutyric acid
  • gamma-Methiol-keto-butyric acid
  • 4-Methylmercapto-2-oxobutyrate
CAS number583-92-6
WeightAverage: 148.18
Monoisotopic: 148.019414812
IUPAC Name4-(methylsulfanyl)-2-oxobutanoic acid
Traditional IUPAC Name2-oxo-4-thiomethylbutyric acid
Chemical FormulaC5H8O3S
Chemical Taxonomy
Description belongs to the class of organic compounds known as thia fatty acids. These are fatty acid derivatives obtained by insertion of a sulfur atom at specific positions in the chain.
KingdomOrganic compounds
Super ClassLipids and lipid-like molecules
ClassFatty Acyls
Sub ClassFatty acids and conjugates
Direct ParentThia fatty acids
Alternative Parents
  • Short-chain keto acid
  • Thia fatty acid
  • Alpha-keto acid
  • Keto acid
  • Alpha-hydroxy ketone
  • Ketone
  • Carboxylic acid derivative
  • Carboxylic acid
  • Dialkylthioether
  • Monocarboxylic acid or derivatives
  • Sulfenyl compound
  • Thioether
  • Hydrocarbon derivative
  • Organic oxide
  • Carbonyl group
  • Organooxygen compound
  • Organosulfur compound
  • Organic oxygen compound
  • Aliphatic acyclic compound
Molecular FrameworkAliphatic acyclic compounds
External Descriptors
Physical Properties
Melting pointNot Available
Experimental Properties
Water SolubilityNot AvailablePhysProp
LogPNot AvailablePhysProp
Predicted Properties
Water Solubility7.44 g/LALOGPS
pKa (Strongest Acidic)3.3ChemAxon
pKa (Strongest Basic)-9.7ChemAxon
Physiological Charge-1ChemAxon
Hydrogen Acceptor Count3ChemAxon
Hydrogen Donor Count1ChemAxon
Polar Surface Area54.37 ŲChemAxon
Rotatable Bond Count4ChemAxon
Refractivity35.07 m³·mol⁻¹ChemAxon
Polarizability14.21 ųChemAxon
Number of Rings0ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Biological Properties
Cellular Locations
  • cytoplasm
Organoleptic PropertiesNot Available
SMPDB Pathways
Methionine metabolism and salvagePW002384 ThumbThumb?image type=greyscaleThumb?image type=simple
KEGG Pathways
Cysteine and methionine metabolismec00270 Map00270
SMPDB Reactions
4-Methylthio-2-oxobutanoate + L-PhenylalanineL-Methionine + 2-Ketobutyric acid
1,2-Dihydroxy-3-keto-5-methylthiopentene + oxygen4-Methylthio-2-oxobutanoate + hydron + Formic acid
KEGG Reactions
5-(methylsulfanyl)-2,3-dioxopentyl phosphate + waterhydron + 4-Methylthio-2-oxobutanoate + phosphate + Formic acid
4-Methylthio-2-oxobutanoate + L-Glutamic acidL-Methionine + Oxoglutaric acid
Intracellular ConcentrationsNot Available
Extracellular ConcentrationsNot Available
Spectrum TypeDescriptionSplash KeyView
GC-MSGC-MS Spectrum - GC-MS (1 MEOX; 1 TMS)splash10-0f79-9620000000-a37f1649aaa00fe355f6JSpectraViewer | MoNA
GC-MSGC-MS Spectrum - GC-MS (1 MEOX; 1 TMS)splash10-0uyr-7940000000-be5c411217da093f2c8aJSpectraViewer | MoNA
GC-MSGC-MS Spectrum - GC-MS (Non-derivatized)splash10-0f79-9620000000-a37f1649aaa00fe355f6JSpectraViewer | MoNA
GC-MSGC-MS Spectrum - GC-MS (Non-derivatized)splash10-0uyr-7940000000-be5c411217da093f2c8aJSpectraViewer | MoNA
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positivesplash10-0005-9200000000-1471d6fe57ac965a873dJSpectraViewer
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (1 TMS) - 70eV, Positivesplash10-0g4j-9400000000-16ddd3b5c053991fac9aJSpectraViewer
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QFT , negativesplash10-0002-9000000000-9b1238b1c990e180a476JSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QTOF 35V, negativesplash10-0002-9000000000-a0fb6b922f7482546f1fJSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 0V, negativesplash10-0002-1900000000-f3facf4268a57538266cJSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 0V, negativesplash10-0002-2900000000-71e4f52b95b529acc1a3JSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 0V, negativesplash10-0002-5900000000-c6325fbf5479dbaa355cJSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 0V, negativesplash10-0002-7900000000-bccb79b226dccd29e36fJSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 1V, negativesplash10-0002-9700000000-8e6b66c2a5dd967a9539JSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 1V, negativesplash10-0002-9500000000-dee1d47be79038a62ac8JSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 1V, negativesplash10-0002-9200000000-184f804af473361e56d4JSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 2V, negativesplash10-0002-9200000000-9f652bc59797907a90e8JSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 2V, negativesplash10-0002-9100000000-2924be77506cc359576fJSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 3V, negativesplash10-0002-9000000000-ac83262a096530d8343fJSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 3V, negativesplash10-0002-9000000000-12841f2d918636eb3ba8JSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - n/a 10V, negativesplash10-0002-9000000000-beb5b9021683b7e71f41JSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - n/a 10V, negativesplash10-0a4i-9000000000-5c4795e954d5c3e9b74eJSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QTOF 35V, positivesplash10-0a6t-0900000000-ed86a80611ad68e921e2JSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 0V, positivesplash10-0006-0900000000-a7b6fa585a128c4bbf25JSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 1V, positivesplash10-0006-0900000000-5d4054fa9cdf6414108dJSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 2V, positivesplash10-0006-0900000000-70154862c61d3d6ece44JSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 2V, positivesplash10-0006-1900000000-4fb317b08aebba3301acJSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 3V, positivesplash10-0006-2900000000-f51204940f05fed4b7fdJSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 3V, positivesplash10-0006-4900000000-f903961d9d95ba1972d5JSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 4V, positivesplash10-0006-6900000000-b83c6421df3d78374fcbJSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 5V, positivesplash10-0006-9800000000-a6c05994216441600396JSpectraViewer | MoNA
LC-MS/MSLC-MS/MS Spectrum - Orbitrap 5V, positivesplash10-0006-9500000000-4c614237f5a6db2521c3JSpectraViewer | MoNA
MSMass Spectrum (Electron Ionization)splash10-0gvp-9300000000-20b6937ce0fd75fa1a65JSpectraViewer | MoNA
MSMass Spectrum (Electron Ionization)splash10-0a4i-8900000000-5b42adf83e422cffefb6JSpectraViewer | MoNA
MSMass Spectrum (Electron Ionization)splash10-0a4i-9800000000-24fa3ff739ff064312abJSpectraViewer | MoNA
  • Herrgard, M. J., Swainston, N., Dobson, P., Dunn, W. B., Arga, K. Y., Arvas, M., Bluthgen, N., Borger, S., Costenoble, R., Heinemann, M., Hucka, M., Le Novere, N., Li, P., Liebermeister, W., Mo, M. L., Oliveira, A. P., Petranovic, D., Pettifer, S., Simeonidis, E., Smallbone, K., Spasic, I., Weichart, D., Brent, R., Broomhead, D. S., Westerhoff, H. V., Kirdar, B., Penttila, M., Klipp, E., Palsson, B. O., Sauer, U., Oliver, S. G., Mendes, P., Nielsen, J., Kell, D. B. (2008). "A consensus yeast metabolic network reconstruction obtained from a community approach to systems biology." Nat Biotechnol 26:1155-1160.18846089
  • Subhi, A. L., Diegelman, P., Porter, C. W., Tang, B., Lu, Z. J., Markham, G. D., Kruger, W. D. (2003). "Methylthioadenosine phosphorylase regulates ornithine decarboxylase by production of downstream metabolites." J Biol Chem 278:49868-49873.14506228
Synthesis Reference:Brodelius, P.; Hagerdal, B.; Mosbach, K. Immobilized whole cells of the yeast Trigonopsis variabilis containing D-amino acid oxidase for the production of a-keto acids. Enzyme Engineering (1980), 5 383-7.
External Links:
Pubchem Compound ID473
Kegg IDC01180
ChemSpider ID460
Wikipedia IDNot Available
BioCyc IDCPD-479


General function:
Involved in catalytic activity
Specific function:
Bifunctional enzyme that catalyzes the enolization of 2,3-diketo-5-methylthiopentyl-1-phosphate (DK-MTP-1-P) into the intermediate 2-hydroxy-3-keto-5-methylthiopentenyl-1-phosphate (HK-MTPenyl-1-P), which is then dephosphorylated to form the acireductone 1,2-dihydroxy-3-keto-5-methylthiopentene (DHK-MTPene)
Gene Name:
Uniprot ID:
Molecular weight:
5-(methylthio)-2,3-dioxopentyl phosphate + H(2)O → 1,2-dihydroxy-5-(methylthio)pent-1-en-3-one + phosphate.
2-Phosphoglycolate + H2O → glycolate + phosphate
General function:
Involved in transferase activity, transferring nitrogenous groups
Specific function:
Has aromatic amino acid transaminase activity and kynurenine aminotransferase activity
Gene Name:
Uniprot ID:
Molecular weight:
An aromatic amino acid + 2-oxoglutarate → an aromatic oxo acid + L-glutamate.