Record Information
Version2.0
Creation Date2015-09-08 17:48:45 -0600
Update Date2015-09-08 17:48:45 -0600
Secondary Accession Numbers
  • ECMDB24053
Identification
Name:Homocysteine
Description:Homocysteine is a sulfur-containing amino acid that arises during methionine metabolism. Although its concentration in plasma is only about 10 micromolar (uM), even moderate hyperhomocysteinemia is associated with increased incidence of cardiovascular disease and Alzheimer's disease. Elevations in plasma homocysteine are commonly found as a result of vitamin deficiencies, polymorphisms of enzymes of methionine metabolism, and renal disease. Pyridoxal, folic acid, riboflavin, and Vitamin B(12) are all required for methionine metabolism, and deficiency of each of these vitamins result in elevated plasma homocysteine. A polymorphism of methylenetetrahydrofolate reductase (C677T), which is quite common in most populations with a homozygosity rate of 10-15 %, is associated with moderate hyperhomocysteinemia, especially in the context of marginal folate intake. Plasma homocysteine is inversely related to plasma creatinine in patients with renal disease. This is due to an impairment in homocysteine removal in renal disease. The role of these factors, and of modifiable lifestyle factors, in affecting methionine metabolism and in determining plasma homocysteine levels is discussed. Homocysteine is an independent cardiovascular disease (CVD) risk factor modifiable by nutrition and possibly exercise. Homocysteine was first identified as an important biological compound in 1932 and linked with human disease in 1962 when elevated urinary homocysteine levels were found in children with mental retardation. This condition, called homocysteinuria, was later associated with premature occlusive CVD, even in children. These observations led to research investigating the relationship of elevated homocysteine levels and CVD in a wide variety of populations including middle age and elderly men and women with and without traditional risk factors for CVD. (PMID 17136938, 15630149).
Structure
Thumb
Synonyms:
ValueSource
2-amino-4-Mercaptobutyric acidChEBI
HcyChEBI
2-amino-4-MercaptobutyrateGenerator
(+-)-HomocysteineHMDB
(S)-2-amino-4-mercapto-ButanoateHMDB
(S)-2-amino-4-mercapto-Butanoic acidHMDB
2-amino-4-mercapto-ButanoateHMDB
2-amino-4-mercapto-Butanoic acidHMDB
2-amino-4-mercapto-Butyric acidHMDB
2-amino-4-mercapto-DL-ButyrateHMDB
2-amino-4-mercapto-DL-Butyric acidHMDB
2-amino-4-SulfanylbutanoateHMDB
2-amino-4-Sulfanylbutanoic acidHMDB
D,L-HomocysteineHMDB
DL-2-amino-4-mercapto-Butyric acidHMDB
DL-2-amino-4-Mercaptobutyric acidHMDB
DL-HomocysteineHMDB
DL-Homocysteine (free base)HMDB
homo-CYSHMDB
L-2-amino-4-mercapto-Butyric acidHMDB
L-HomocysteineHMDB
Usaf b-12HMDB
Homocysteine, L isomerMeSH
Homocysteine, L-isomerMeSH
2 amino 4 Mercaptobutyric acidMeSH
L-Isomer homocysteineMeSH
Chemical Formula:C4H9NO2S
Weight:Average: 135.185
Monoisotopic: 135.035399227
InChI Key:FFFHZYDWPBMWHY-UHFFFAOYSA-N
InChI:InChI=1S/C4H9NO2S/c5-3(1-2-8)4(6)7/h3,8H,1-2,5H2,(H,6,7)
CAS number:Not Available
IUPAC Name:2-amino-4-sulfanylbutanoic acid
Traditional IUPAC Name:homocysteine
SMILES:NC(CCS)C(O)=O
Chemical Taxonomy
DescriptionThis compound belongs to the class of organic compounds known as alpha amino acids. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon).
KingdomOrganic compounds
Super ClassOrganic acids and derivatives
ClassCarboxylic acids and derivatives
Sub ClassAmino acids, peptides, and analogues
Direct ParentAlpha amino acids
Alternative Parents
Substituents
  • Alpha-amino acid
  • Thia fatty acid
  • Fatty acyl
  • Fatty acid
  • Amino acid
  • Alkylthiol
  • Carboxylic acid
  • Monocarboxylic acid or derivatives
  • Organic nitrogen compound
  • Hydrocarbon derivative
  • Primary amine
  • Organosulfur compound
  • Organooxygen compound
  • Organonitrogen compound
  • Organic oxide
  • Primary aliphatic amine
  • Organopnictogen compound
  • Carbonyl group
  • Amine
  • Organic oxygen compound
  • Aliphatic acyclic compound
Molecular FrameworkAliphatic acyclic compounds
External Descriptors
Physical Properties
State:Not Available
Charge:0
Melting point:Not Available
Experimental Properties:
PropertyValueSource
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
Refractivity32.94 m³·mol⁻¹ChemAxon
Polarizability13.44 ųChemAxon
Number of Rings0ChemAxon
Bioavailability1ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Biological Properties
Cellular Locations:Cytoplasm
Reactions:
SMPDB Pathways:
One Carbon Pool by Folate IPW001735 ThumbThumb?image type=greyscaleThumb?image type=simple
Quorum SensingPW000836 ThumbThumb?image type=greyscaleThumb?image type=simple
S-adenosyl-L-methionine cyclePW002080 ThumbThumb?image type=greyscaleThumb?image type=simple
methionine biosynthesisPW000814 ThumbThumb?image type=greyscaleThumb?image type=simple
KEGG Pathways:Not Available
EcoCyc Pathways:Not Available
Concentrations
Not Available
Spectra
Spectra:
Spectrum TypeDescriptionSplash Key
GC-MSGC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies) (Non-derivatized)splash10-0059-0930000000-b4e6d47b81f1810f1f31View in MoNA
GC-MSGC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies) (Non-derivatized)splash10-004i-0910000000-7b3c5664e3b6b1930674View in MoNA
GC-MSGC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies) (Non-derivatized)splash10-004i-0910000000-0dbe4ce28b468fb874f0View in MoNA
GC-MSGC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies) (3 TMS)splash10-00di-9730000000-952f5d413ee77e474820View in MoNA
GC-MSGC-MS Spectrum - GC-MS (2 TMS)splash10-03yi-3900000000-b5bcb65d1cfa2f5b4a83View in MoNA
GC-MSGC-MS Spectrum - GC-MS (3 TMS)splash10-0059-1950000000-09d1f6d02198624082eaView in MoNA
GC-MSGC-MS Spectrum - EI-B (Non-derivatized)splash10-0059-0981000000-c6d399e1bddf1f7bc057View in MoNA
GC-MSGC-MS Spectrum - GC-EI-TOF (Non-derivatized)splash10-0059-0930000000-b4e6d47b81f1810f1f31View in MoNA
GC-MSGC-MS Spectrum - GC-EI-TOF (Non-derivatized)splash10-00di-9730000000-952f5d413ee77e474820View in MoNA
GC-MSGC-MS Spectrum - GC-MS (Non-derivatized)splash10-03yi-3900000000-b5bcb65d1cfa2f5b4a83View in MoNA
GC-MSGC-MS Spectrum - GC-MS (Non-derivatized)splash10-0059-1950000000-09d1f6d02198624082eaView in MoNA
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positivesplash10-0006-9000000000-1f800d28bca4b2b7a49fView in MoNA
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (1 TMS) - 70eV, Positivesplash10-00dj-9700000000-368cb861e20b107da57aView in MoNA
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 10V, Positive (Annotated)splash10-0006-9300000000-a8fd35730e901755194eView in MoNA
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 25V, Positive (Annotated)splash10-0a4l-9000000000-0e79cc37f5cb8f05cd37View in MoNA
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 40V, Positive (Annotated)splash10-052b-9000000000-694b412a6bed9a77958eView in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Positivesplash10-000f-9700000000-2e1b7e55ed5da543b557View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Positivesplash10-0006-9100000000-7e82906cac0f17bd5123View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Positivesplash10-0bvi-9000000000-7c49d870f77950b940a5View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Negativesplash10-001i-3900000000-4e1b7a42d769b9c2574cView in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Negativesplash10-001i-7900000000-35b3c5fd78dec88148fbView in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Negativesplash10-001i-9000000000-533b0cacf1e578850e94View in MoNA
1D NMR1H NMR SpectrumNot AvailableView in JSpectraViewer
1D NMR1H NMR SpectrumNot AvailableView in JSpectraViewer
1D NMR1H NMR SpectrumNot AvailableView in JSpectraViewer
1D NMR13C NMR SpectrumNot AvailableView in JSpectraViewer
2D NMR[1H,13C] 2D NMR SpectrumNot AvailableView in JSpectraViewer
References
References:Not Available
Synthesis Reference:Not Available
Material Safety Data Sheet (MSDS)Not Available
External Links:
ResourceLink
CHEBI ID17230
HMDB IDHMDB0000742
Pubchem Compound ID778
Kegg IDC05330
ChemSpider ID757
Wikipedia IDHomocysteine
BioCyc IDNot Available

Enzymes

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.