Homocysteine
Athanor · official
C4H9NO2S · 135.19 g/mol
IUPAC name: (2S)-2-amino-4-sulfanylbutanoic acid
Also called Hcy
WarningHarmful if swallowedNames and identifiers
- IUPAC name
- (2S)-2-amino-4-sulfanylbutanoic acid
- Synonyms
- Hcy, L-Homocysteine, (2S)-2-amino-4-sulfanylbutanoic acid
+ 35 more
2-AMINO-4-MERCAPTO-BUTYRIC ACID, 0LVT1QZ0BA, Homocysteine, L-, homo-cys, DTXSID3041039, CHEBI:17588, L-2-Amino-4-mercaptobutyric acid, Butyric acid, 2-amino-4-mercapto-, 2-amino-4-sulfanylbutanoate, 2-amino-4-mercapto-Butanoic acid, NSC-43117, NSC-118376, L-Isomer Homocysteine, (2S)-2-azaniumyl-4-sulfanylbutanoate, CHEBI:17230, 2 amino 4 mercaptobutyric acid, Butanoic acid, 2-amino-4-mercapto-, Homocysteine, L, RefChem:788455, DTXCID1021039, 227-891-0, 2-Amino-4-Mercaptobutyric Acid, 2-Amino-4-Sulfanylbutanoic Acid, (s)-2-amino-4-mercaptobutanoic acid, MFCD00151320, CHEMBL469662, (S)-2-Amino-4-mercaptobutyric acid, HCS, Homocysteine (VAN), UNII-0LVT1QZ0BA, homocystein, Butyric acid, 2-amino-4-mercapto-, L-, EINECS 227-891-0, NSC 43117, NSC 118376
- Molecular formula
- C4H9NO2S
- Empirical formula
- C4H9NO2S
- Molecular weight
- 135.19 g/mol
- Exact mass
- 135.03540
- CAS number
- 6027-13-0
- PubChem CID
- 91552
- Canonical SMILES
- C(CS)C(C(=O)O)N
- Isomeric SMILES
- C(CS)[C@@H](C(=O)O)N
- InChI
- InChI=1S/C4H9NO2S/c5-3(1-2-8)4(6)7/h3,8H,1-2,5H2,(H,6,7)/t3-/m0/s1
- InChIKey
- FFFHZYDWPBMWHY-VKHMYHEASA-N
- Molfile
Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.
Calculated
- Heavy atoms
- 8
- Rings
- 0
- Aromatic rings
- 0
- Fraction sp³ carbons (Fsp3)
- 0.75
- H-bond donors
- 3
- H-bond acceptors
- 3 computed here · PubChem 4
- Rotatable bonds
- 3
- TPSA (Ų)
- 63.3 computed here · PubChem 64.3
- Formal charge
- 0
- XLogP3
- -3.4 PubChem
- Complexity
- 86 PubChem
- Stereocenters
- 1 definedCIP: C4: S
- Double-bond geometry
- None specified
- Point group
- C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)
Elemental analysis
- C35.54%
- H6.71%
- N10.36%
- O23.67%
- S23.72%
Isotope pattern
Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.
Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.
Predicted
- log P
- -0.28 Crippen (Wildman and Crippen 1999)
- log S (water solubility)
- -0.3 ESOL (Delaney 2004), log mol/L
- Synthetic accessibility
- 3.09 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)
Drug-likeness: Lipinski’s rule of five
- Molecular weight ≤ 500: 135.19
- log P ≤ 5 (Crippen): -0.28
- H-bond donors ≤ 5: 3
- H-bond acceptors ≤ 10: 3
Passes all four rules.
¹³C NMR shifts, predicted
Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.
Safety
Warning
Most widely reported: 41 company reports to ECHA. Source [1].
- Harmful or irritant
- H302Harmful if swallowed (97.6% of reports)
Precautionary statements: P264, P270, P301+P317, P330, P501
View all classifications (2)
- [1] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 2.4% (1 of 41) of reports.
- [1] European Chemicals Agency (ECHA) · 41 reports · WarningH302
Safety data sheets on the supplier’s page: 001Chemical, abcr GmbH, Pi Chemicals.
Always read the supplier’s safety data sheet before working with it.
Spectra
- 1H NMRHuman Metabolome Database (HMDB) (Varian · 500 MHz · Water) · Human Metabolome Database (HMDB) (JEOL · 400 MHz · D2O) · Human Metabolome Database (HMDB) (Bruker · D2O)
- 13C NMRHuman Metabolome Database (HMDB) (Bruker · D2O)
- 1H-13C NMRHuman Metabolome Database (HMDB) (Bruker · 600 MHz · Water)
- GC-MSHuman Metabolome Database (HMDB) (GC-EI-TOF · positive) · MassBank Europe (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies · GC-EI-TOF · POSITIVE) · MassBank of North America (MoNA) (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies · GC-EI-TOF · positive) · MassBank of North America (MoNA) (GC-MS) · MassBank of North America (MoNA) (GC-MS)
- MS-MSHuman Metabolome Database (HMDB) (Positive) · Human Metabolome Database (HMDB) (LC-ESI-ITFT · positive) · Human Metabolome Database (HMDB) (LC-ESI-ITFT · positive) · Human Metabolome Database (HMDB) (Quattro_QQQ · Positive) · Human Metabolome Database (HMDB) (Quattro_QQQ · Positive) · Human Metabolome Database (HMDB) (Quattro_QQQ · Positive)
- LC-MSMassBank Europe (LTQ Orbitrap XL, Thermo Scientfic · LC-ESI-ITFT · POSITIVE) · MassBank Europe (LTQ Orbitrap XL, Thermo Scientfic · LC-ESI-ITFT · POSITIVE) · MassBank Europe (LTQ Orbitrap XL, Thermo Scientfic · LC-ESI-ITFT · POSITIVE) · MassBank Europe (LTQ Orbitrap XL, Thermo Scientfic · LC-ESI-ITFT · POSITIVE) · MassBank Europe (LTQ Orbitrap XL, Thermo Scientfic · LC-ESI-ITFT · POSITIVE) · MassBank of North America (MoNA) (LTQ Orbitrap XL, Thermo Scientfic · LC-ESI-ITFT · ESI)
Experimental spectra held by these sources; each link opens the source's own record.
Literature
Reading PubChem, OpenAlex and GSRS…
Bioactivity
Reading ChEMBL…
References
- [1]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
- [2]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
- [3]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
- [4]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
- ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
- ·Literature on PubChem
Data last updated 2026-10-14.