Record Information
Version2.0
Creation Date2012-05-31 10:22:38 -0600
Update Date2015-09-13 12:56:06 -0600
Secondary Accession Numbers
  • ECMDB00165
Identification
Name:L-Homocysteine
Description:Homocysteine is a thiol-containing amino acid formed by a demethylation of methionine. Homocysteine is a variant of the amino acid cysteine, differing in that its side-chain contains an additional methylene (-CH2-) group before the thiol (-SH) group. In Escherichia coli homocysteine (Hcy) is the last intermediate on the methionine biosynthetic pathway.
Structure
Thumb
Synonyms:
  • (+-)-homocysteine
  • (S)-2-amino-4-mercapto-Butanoate
  • (S)-2-amino-4-mercapto-Butanoic acid
  • (S)-2-Amino-4-mercaptobutanoate
  • (S)-2-Amino-4-mercaptobutanoic acid
  • (S)-Homocysteine
  • 2-amino-4-mercapto-Butanoate
  • 2-amino-4-mercapto-Butanoic acid
  • 2-Amino-4-mercapto-Butyrate
  • 2-Amino-4-mercapto-Butyric acid
  • 2-amino-4-mercapto-DL-Butyrate
  • 2-amino-4-mercapto-DL-Butyric acid
  • 2-Amino-4-mercapto-L-butyrate
  • 2-Amino-4-mercapto-L-butyric acid
  • 2-Amino-4-mercaptobutyrate
  • 2-Amino-4-mercaptobutyric acid
  • 2-amino-4-sulfanylbutanoate
  • 2-amino-4-sulfanylbutanoic acid
  • 2-amino-4-Sulphanylbutanoate
  • 2-amino-4-Sulphanylbutanoic acid
  • D,l-homocysteine
  • DL-2-amino-4-mercapto-Butyrate
  • DL-2-amino-4-mercapto-Butyric acid
  • DL-2-amino-4-Mercaptobutyrate
  • DL-2-Amino-4-mercaptobutyric acid
  • DL-Homocysteine
  • DL-homocysteine (free base)
  • HCY
  • Homo-cys
  • Homocysteine
  • L-2-Amino-4-mercapto-Butyrate
  • L-2-Amino-4-mercapto-Butyric acid
  • L-2-Amino-4-mercaptobutyrate
  • L-2-Amino-4-mercaptobutyric acid
  • L-Homocysteine
  • Usaf B-12
Chemical Formula:C4H9NO2S
Weight:Average: 135.185
Monoisotopic: 135.035399227
InChI Key:FFFHZYDWPBMWHY-VKHMYHEASA-N
InChI:InChI=1S/C4H9NO2S/c5-3(1-2-8)4(6)7/h3,8H,1-2,5H2,(H,6,7)/t3-/m0/s1
CAS number:6027-13-0
IUPAC Name:(2S)-2-amino-4-sulfanylbutanoic acid
Traditional IUPAC Name:L-homocysteine
SMILES:N[C@@H](CCS)C(O)=O
Chemical Taxonomy
DescriptionThis compound belongs to the class of chemical entities known as l-alpha-amino acids. These are alpha amino acids which have the L-configuration of the alpha-carbon atom.
KingdomChemical entities
Super ClassOrganic compounds
ClassOrganic acids and derivatives
Sub ClassCarboxylic acids and derivatives
Direct ParentL-alpha-amino acids
Alternative Parents
Substituents
  • L-alpha-amino acid
  • Thia fatty acid
  • Fatty acid
  • Fatty acyl
  • Amino acid
  • Alkylthiol
  • Carboxylic acid
  • Monocarboxylic acid or derivatives
  • Organic nitrogen compound
  • Hydrocarbon derivative
  • Organic oxide
  • Primary amine
  • Organosulfur compound
  • Organooxygen compound
  • Organonitrogen compound
  • Organopnictogen compound
  • Primary aliphatic amine
  • Organic oxygen compound
  • Carbonyl group
  • Amine
  • Aliphatic acyclic compound
Molecular FrameworkAliphatic acyclic compounds
External Descriptors
Physical Properties
State:Solid
Charge:0
Melting point:232.6 °C
Experimental Properties:
PropertyValueSource
LogP:-2.538PhysProp
Predicted Properties
PropertyValueSource
Water Solubility14.8 g/LALOGPS
logP-2.3ALOGPS
logP-2.6ChemAxon
logS-0.96ALOGPS
pKa (Strongest Acidic)2.46ChemAxon
pKa (Strongest Basic)9.41ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count3ChemAxon
Hydrogen Donor Count3ChemAxon
Polar Surface Area63.32 ŲChemAxon
Rotatable Bond Count3ChemAxon
Refractivity32.93 m³·mol⁻¹ChemAxon
Polarizability13.54 ųChemAxon
Number of Rings0ChemAxon
Bioavailability1ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Biological Properties
Cellular Locations:Cytoplasm
Reactions:
L-Cystathionine + Water > L-Homocysteine + Ammonium + Pyruvic acid
5-Methyltetrahydrofolic acid + L-Homocysteine <> Hydrogen ion + L-Methionine + Tetrahydrofolic acid
L-Homocysteine + S-Methylmethionine > Hydrogen ion +2 L-Methionine
S-Adenosylmethionine + L-Homocysteine + S-Methylmethionine <> S-Adenosylhomocysteine + Hydrogen ion + L-Methionine
S-Ribosyl-L-homocysteine > 4,5-Dihydroxy-2,3-pentanedione + L-Homocysteine
S-Adenosylmethionine + L-Homocysteine <> S-Adenosylhomocysteine + L-Methionine
5-Methyltetrahydrofolic acid + L-Homocysteine <> Tetrahydrofolic acid + L-Methionine
Cystathionine + Water <> L-Homocysteine + Ammonia + Pyruvic acid
L-Cystathionine + Water <> L-Homocysteine + Ammonia + Pyruvic acid
O-Succinyl-L-homoserine + Hydrogen sulfide <> L-Homocysteine + Succinic acid
S-Ribosyl-L-homocysteine <> (4S)-4,5-Dihydroxypentan-2,3-dione + L-Homocysteine
5-Methyltetrahydropteroyltri-L-glutamic acid + L-Homocysteine <> Tetrahydropteroyltri-L-glutamic acid + L-Methionine
L-Cystathionine + Water > Hydrogen ion + Pyruvic acid + Ammonia + L-Homocysteine
L-Homocysteine + 5-Methyltetrahydropteroyltri-L-glutamic acid > L-Methionine + tetrahydropteroyl tri-L-glutamate
L-Homocysteine + 5-Methyltetrahydrofolic acid L-Methionine + Tetrahydrofolic acid
L-Homocysteine + S-Adenosylmethionine Hydrogen ion + L-Methionine + S-Adenosylhomocysteine
S-methyl-L-methionine + L-Homocysteine Hydrogen ion + L-Methionine
S-Ribosyl-L-homocysteine > L-Homocysteine + 4,5-Dihydroxy-2,3-pentanedione
S-Ribosyl-L-homocysteine > L-Homocysteine + (4S)-4,5-Dihydroxypentan-2,3-dione
L-Cystathionine + Water > L-Homocysteine + Ammonia + Pyruvic acid
L-Cystathionine + Water > L-Homocysteine + Ammonia + Pyruvic acid
5-methyltetrahydropteroyltri-L-glutamate + L-Homocysteine > tetrahydropteroyltri-L-glutamate + L-Methionine
5-Methyltetrahydrofolic acid + L-Homocysteine > Tetrahydrofolic acid + L-Methionine
S-methyl-L-methionine + L-Homocysteine >2 L-Methionine
L-Cystathionine + Water + 2-Aminoacrylic acid + 2-Iminopropanoate <> L-Homocysteine + Pyruvic acid + Ammonia
SMPDB Pathways:
Nitrogen metabolismPW000755 ThumbThumb?image type=greyscaleThumb?image type=simple
One carbon pool by folatePW000773 ThumbThumb?image type=greyscaleThumb?image type=simple
Sulfur metabolismPW000922 ThumbThumb?image type=greyscaleThumb?image type=simple
KEGG Pathways:
EcoCyc Pathways:
Concentrations
ConcentrationStrainMediaGrowth StatusGrowth SystemTemperatureDetails
370± 0 uMK12 NCM3722Gutnick minimal complete medium (4.7 g/L KH2PO4; 13.5 g/L K2HPO4; 1 g/L K2SO4; 0.1 g/L MgSO4-7H2O; 10 mM NH4Cl) with 4 g/L glucoseMid-Log PhaseShake flask and filter culture37 oCPMID: 19561621
Find out more about how we convert literature concentrations.
Spectra
Spectra:
Spectrum TypeDescriptionSplash Key
GC-MSGC-MS Spectrum - GC-EI-TOF (Non-derivatized)splash10-004i-0920000000-20fbffbe76510c066e6fView in MoNA
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positivesplash10-0006-9000000000-1f800d28bca4b2b7a49fView in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-ITFT , positivesplash10-014l-4900000000-c50d79ba3a5013bcf29fView in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-ITFT , positivesplash10-000i-9000000000-025c9e1f4fb58138c43bView in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-ITFT , positivesplash10-014i-4900000000-33f205e002f49f034764View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Positivesplash10-00ko-9800000000-80a1c80328e8836233a4View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Positivesplash10-0006-9100000000-1f611da44349ffdfaefeView in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Positivesplash10-0bvi-9000000000-c9d62a66522e46a17f56View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Negativesplash10-001i-3900000000-e8322d5858cba16a3bd2View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Negativesplash10-00lr-6900000000-e0190a1cc33e605bac0aView in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Negativesplash10-001i-9000000000-900bb5d8fb11bec02e39View in MoNA
References
References:
  • Bennett, B. D., Kimball, E. H., Gao, M., Osterhout, R., Van Dien, S. J., Rabinowitz, J. D. (2009). "Absolute metabolite concentrations and implied enzyme active site occupancy in Escherichia coli." Nat Chem Biol 5:593-599. Pubmed: 19561621
  • Kanehisa, M., Goto, S., Sato, Y., Furumichi, M., Tanabe, M. (2012). "KEGG for integration and interpretation of large-scale molecular data sets." Nucleic Acids Res 40:D109-D114. Pubmed: 22080510
  • Keseler, I. M., Collado-Vides, J., Santos-Zavaleta, A., Peralta-Gil, M., Gama-Castro, S., Muniz-Rascado, L., Bonavides-Martinez, C., Paley, S., Krummenacker, M., Altman, T., Kaipa, P., Spaulding, A., Pacheco, J., Latendresse, M., Fulcher, C., Sarker, M., Shearer, A. G., Mackie, A., Paulsen, I., Gunsalus, R. P., Karp, P. D. (2011). "EcoCyc: a comprehensive database of Escherichia coli biology." Nucleic Acids Res 39:D583-D590. Pubmed: 21097882
  • van der Werf, M. J., Overkamp, K. M., Muilwijk, B., Coulier, L., Hankemeier, T. (2007). "Microbial metabolomics: toward a platform with full metabolome coverage." Anal Biochem 370:17-25. Pubmed: 17765195
  • Vijayendran, C., Barsch, A., Friehs, K., Niehaus, K., Becker, A., Flaschel, E. (2008). "Perceiving molecular evolution processes in Escherichia coli by comprehensive metabolite and gene expression profiling." Genome Biol 9:R72. Pubmed: 18402659
  • Winder, C. L., Dunn, W. B., Schuler, S., Broadhurst, D., Jarvis, R., Stephens, G. M., Goodacre, R. (2008). "Global metabolic profiling of Escherichia coli cultures: an evaluation of methods for quenching and extraction of intracellular metabolites." Anal Chem 80:2939-2948. Pubmed: 18331064
Synthesis Reference:Biochem Prepn. 5 93 (1957)
Material Safety Data Sheet (MSDS)Download (PDF)
External Links:
ResourceLink
CHEBI ID17588
HMDB IDHMDB00742
Pubchem Compound ID91552
Kegg IDC00155
ChemSpider ID82666
WikipediaHomocysteine
BioCyc IDHOMO-CYS
EcoCyc IDHOMO-CYS
Ligand ExpoHCS

Enzymes

General function:
Involved in pyridoxal phosphate binding
Specific function:
O(4)-succinyl-L-homoserine + L-cysteine = L- cystathionine + succinate
Gene Name:
metB
Uniprot ID:
P00935
Molecular weight:
41550
Reactions
O(4)-succinyl-L-homoserine + L-cysteine = L-cystathionine + succinate.
General function:
Involved in pyridoxal phosphate binding
Specific function:
L-cystathionine + H(2)O = L-homocysteine + NH(3) + pyruvate
Gene Name:
metC
Uniprot ID:
P06721
Molecular weight:
43212
Reactions
L-cystathionine + H(2)O = L-homocysteine + NH(3) + pyruvate.
General function:
Involved in methionine synthase activity
Specific function:
Catalyzes the transfer of a methyl group from methyl- cobalamin to homocysteine, yielding enzyme-bound cob(I)alamin and methionine. Subsequently, remethylates the cofactor using methyltetrahydrofolate
Gene Name:
metH
Uniprot ID:
P13009
Molecular weight:
135996
Reactions
5-methyltetrahydrofolate + L-homocysteine = tetrahydrofolate + L-methionine.
General function:
Involved in transferase activity
Specific function:
Acts as a beta-cystathionase and as a repressor of the maltose regulon
Gene Name:
malY
Uniprot ID:
P23256
Molecular weight:
43641
Reactions
L-cystathionine + H(2)O = L-homocysteine + NH(3) + pyruvate.
General function:
Involved in 5-methyltetrahydropteroyltriglutamate-homocysteine S-methyltransferase activity
Specific function:
Catalyzes the transfer of a methyl group from 5- methyltetrahydrofolate to homocysteine resulting in methionine formation
Gene Name:
metE
Uniprot ID:
P25665
Molecular weight:
84673
Reactions
5-methyltetrahydropteroyltri-L-glutamate + L-homocysteine = tetrahydropteroyltri-L-glutamate + L-methionine.
General function:
Involved in catalytic activity
Specific function:
Involved in the synthesis of autoinducer 2 (AI-2) which is secreted by bacteria and is used to communicate both the cell density and the metabolic potential of the environment. The regulation of gene expression in response to changes in cell density is called quorum sensing. Catalyzes the transformation of S-ribosylhomocysteine (RHC) to homocysteine (HC) and 4,5- dihydroxy-2,3-pentadione (DPD)
Gene Name:
luxS
Uniprot ID:
P45578
Molecular weight:
19416
Reactions
S-(5-deoxy-D-ribos-5-yl)-L-homocysteine = L-homocysteine + (4S)-4,5-dihydroxypentan-2,3-dione.
General function:
Involved in homocysteine S-methyltransferase activity
Specific function:
Catalyzes methyl transfer from S-methylmethionine or S- adenosylmethionine (less efficient) to homocysteine, selenohomocysteine and less efficiently selenocysteine
Gene Name:
mmuM
Uniprot ID:
Q47690
Molecular weight:
33422
Reactions
S-methyl-L-methionine + L-homocysteine = 2 L-methionine.