You are using an unsupported browser. Please upgrade your browser to a newer version to get the best experience on Human Metabolome Database.
Record Information
Creation Date2005-11-16 15:48:42 UTC
Update Date2017-03-02 21:25:59 UTC
Secondary Accession NumbersNone
Metabolite Identification
Common NameDL-Homocystine
DescriptionHomocystine is the double-bonded form of homocysteine, but it occurs only transiently before being converted to the harmless cystathionine via a vitamin B6-dependent enzyme. Homocystine and homocysteine-cysteine mixed disulfide account for >98% of total homocysteine in plasma from healthy individuals. (PMID 11592966 ). Oxidation of low-density lipoprotein (LDL) is thought to be a major factor in the pathophysiology of atherosclerosis. Elevated plasma homocysteine is an accepted risk factor for atherosclerosis, and may act through LDL oxidation, although this is controversial. However, the major thiol in plasma is cysteine, which is present at concentrations approximately 10 times greater than homocysteine; therefore homocystine in plasma is insignificant, and consequently homocystine is unlikely to influence LDL oxidation in vivo. (PMID 14732479 ). Increasing evidence supports a role for an elevation of homocysteine in schizophrenia. It has been demonstrated that neural tube defects are related to a genetic defect in homocysteine metabolism. Sufficient intake of folic acid is believed to reduce this risk by enhancing methylation of homocysteine and its conversion to methionine, thereby compensating for this genetic defect. Plasma homocysteine levels are elevated when folate levels are in the lower half of the normal range. (PMID 16143442 ).
4,4'-Dithiobis(2-aminobutyric acid)ChEBI
Chemical FormulaC8H16N2O4S2
Average Molecular Weight268.354
Monoisotopic Molecular Weight268.05514839
IUPAC Name2-amino-4-[(3-amino-3-carboxypropyl)disulfanyl]butanoic acid
Traditional Namehomocystine
CAS Registry Number870-93-9
InChI Identifier
Chemical Taxonomy
DescriptionThis compound belongs to the class of chemical entities 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).
KingdomChemical entities
Super ClassOrganic compounds
ClassOrganic acids and derivatives
Sub ClassCarboxylic acids and derivatives
Direct ParentAlpha amino acids
Alternative Parents
  • Alpha-amino acid
  • Thia fatty acid
  • Dicarboxylic acid or derivatives
  • Fatty acid
  • Fatty acyl
  • Organic disulfide
  • Amino acid
  • Dialkyldisulfide
  • Sulfenyl compound
  • Carboxylic acid
  • Organic oxide
  • Organopnictogen compound
  • Primary amine
  • Organosulfur compound
  • Organooxygen compound
  • Organonitrogen compound
  • Primary aliphatic amine
  • Organic oxygen compound
  • Carbonyl group
  • Organic nitrogen compound
  • Amine
  • Hydrocarbon derivative
  • Aliphatic acyclic compound
Molecular FrameworkAliphatic acyclic compounds
External Descriptors
StatusDetected and Quantified
  • Endogenous
  • Protein synthesis, amino acid biosynthesis
ApplicationNot Available
Cellular locations
  • Cytoplasm
Physical Properties
Experimental Properties
Melting Point263 - 265 °CNot Available
Boiling PointNot AvailableNot Available
Water SolubilityNot AvailableNot Available
LogPNot AvailableNot Available
Predicted Properties
Water Solubility4.5 mg/mLALOGPS
pKa (Strongest Acidic)1.8ChemAxon
pKa (Strongest Basic)9.8ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count6ChemAxon
Hydrogen Donor Count4ChemAxon
Polar Surface Area126.64 Å2ChemAxon
Rotatable Bond Count9ChemAxon
Refractivity64.38 m3·mol-1ChemAxon
Polarizability26.92 Å3ChemAxon
Number of Rings0ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Spectrum TypeDescriptionSplash Key
GC-MSGC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies)splash10-004i-0920000000-4772adba6d14b0bf412bView in MoNA
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 10V, Positive (Annotated)splash10-000i-0900000000-5c60c8ff83dddb24602eView in MoNA
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 25V, Positive (Annotated)splash10-000i-9200000000-2895a3e74d847e15c6a1View in MoNA
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 40V, Positive (Annotated)splash10-000i-9000000000-0a6bc3cbbfaf644160a3View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 10V, Negativesplash10-014i-0190000000-60f50f1524147fa8c11cView in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 20V, Negativesplash10-001i-2920000000-bd3949a66bce9cbb215fView in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 30V, Negativesplash10-06e9-9720000000-7031c8ff553e104dc664View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 40V, Negativesplash10-00di-9210000000-eff737edd37664256745View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ (API3000, Applied Biosystems) 50V, Negativesplash10-00di-9000000000-560f6dc8247244af6cb4View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ , negativesplash10-014i-0190000000-dc9f97c5c65a44240b15View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ , negativesplash10-001i-2920000000-92fb65949be59e182083View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QQ , negativesplash10-00di-9210000000-903e4d0b7abc5500ebf1View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-TOF , negativesplash10-01x0-6900000000-d82f9d3a2cbf6b1216f0View in MoNA
1D NMR1H NMR SpectrumNot Available
2D NMR[1H,13C] 2D NMR SpectrumNot Available
Biological Properties
Cellular Locations
  • Cytoplasm
Biofluid Locations
  • Blood
  • Urine
Tissue LocationNot Available
PathwaysNot Available
Normal Concentrations
BloodDetected and Quantified9.8 +/- 2.8 uMAdult (>18 years old)BothNormal details
UrineDetected and Quantified0.21 umol/mmol creatinineAdult (>18 years old)BothNormal details
Abnormal Concentrations
BloodDetected and Quantified3.0 (0.0-5.0) uMAdult (>18 years old)BothMethylmalonic acidemia and homocystinuria details
BloodDetected and Quantified122.5 (12.00-233.00) uMChildren (1-13 years old)BothHomocystinuria details
BloodDetected and Quantified5.00 uMAdult (>18 years old)BothHomocystinuria due to defect of N(5,10)-methylene THF deficiency details
UrineDetected and Quantified8.8 umol/mmol creatinineAdult (>18 years old)BothMethylenetetrahydrofolate reductase deficiency details
UrineDetected and Quantified22.73 (1-44.47) umol/mmol creatinineChildren (1-13 years old)BothHomocystinuria details
Associated Disorders and Diseases
Disease References
  1. Andersson HC, Shapira E: Biochemical and clinical response to hydroxocobalamin versus cyanocobalamin treatment in patients with methylmalonic acidemia and homocystinuria (cblC). J Pediatr. 1998 Jan;132(1):121-4. [PubMed:9470012 ]
  2. MetaGene [Link]
Methylmalonic acidemia
  1. Andersson HC, Shapira E: Biochemical and clinical response to hydroxocobalamin versus cyanocobalamin treatment in patients with methylmalonic acidemia and homocystinuria (cblC). J Pediatr. 1998 Jan;132(1):121-4. [PubMed:9470012 ]
Methylenetetrahydrofolate reductase deficiency
  1. MetaGene [Link]
Homocystinuria due to defect of N(5,10)-methylene THF deficiency
  1. MetaGene [Link]
Associated OMIM IDs
  • 236200 (Homocystinuria)
  • 251000 (Methylmalonic acidemia)
  • 236250 (Homocystinuria due to defect of N(5,10)-methylene THF deficiency)
  • 236250 (Methylenetetrahydrofolate reductase deficiency)
DrugBank IDNot Available
DrugBank Metabolite IDNot Available
Phenol Explorer Compound IDNot Available
Phenol Explorer Metabolite IDNot Available
FoodDB IDFDB022123
KNApSAcK IDNot Available
Chemspider ID9616
KEGG Compound IDC01817
BioCyc IDNot Available
BiGG IDNot Available
Wikipedia LinkHomocystine
NuGOwiki LinkHMDB00575
Metagene LinkHMDB00575
PubChem Compound10010
PDB IDNot Available
ChEBI ID17485
Synthesis ReferenceLang, K.; Keller, C. Effect of the cyclophorase system on sulfur-containing amino acids. Biochemische Zeitschrift (1955), 327 202-8.
Material Safety Data Sheet (MSDS)Not Available
General References
  1. Ohdoi C, Nyhan WL, Kuhara T: Chemical diagnosis of Lesch-Nyhan syndrome using gas chromatography-mass spectrometry detection. J Chromatogr B Analyt Technol Biomed Life Sci. 2003 Jul 15;792(1):123-30. [PubMed:12829005 ]
  2. Wilcken DE, Gupta VJ: Sulphr containing amino acids in chronic renal failure with particular reference to homocystine and cysteine-homocysteine mixed disulphide. Eur J Clin Invest. 1979 Aug;9(4):301-7. [PubMed:118020 ]
  3. Sengupta S, Wehbe C, Majors AK, Ketterer ME, DiBello PM, Jacobsen DW: Relative roles of albumin and ceruloplasmin in the formation of homocystine, homocysteine-cysteine-mixed disulfide, and cystine in circulation. J Biol Chem. 2001 Dec 14;276(50):46896-904. Epub 2001 Oct 9. [PubMed:11592966 ]
  4. Nakano E, Williamson MP, Williams NH, Powers HJ: Copper-mediated LDL oxidation by homocysteine and related compounds depends largely on copper ligation. Biochim Biophys Acta. 2004 Jan 20;1688(1):33-42. [PubMed:14732479 ]
  5. Brown AS, Susser ES: Homocysteine and schizophrenia: from prenatal to adult life. Prog Neuropsychopharmacol Biol Psychiatry. 2005 Sep;29(7):1175-80. [PubMed:16143442 ]