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Chemical substance record

L-cystine

56-89-3C6H12N2O4S2240.306 g/mol
Organic/Inorganic Small MoleculeChEBI source record

The L-enantiomer of the sulfur-containing amino acid cystine. — ChEBI

Safety references

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Identity & molecular properties

Source-linked values
CAS number56-89-3ChEBI ↗
Molecular formulaC6H12N2O4S2ChEBI ↗
Molar mass240.306 g/molChEBI ↗
Monoisotopic mass240.02385 DaChEBI ↗
Formal charge0ChEBI ↗
ChEBI identifierCHEBI:16283ChEBI ↗

Cross-source molecular data

PubChem
Molar mass240.3 g/molPubChem ↗
Exact mass240.02384922 DaPubChem ↗
Computed XLogP-6.3PubChem ↗
Topological polar surface area (Ų)177PubChem ↗
H-bond donors4PubChem ↗
H-bond acceptors8PubChem ↗
Rotatable bonds7PubChem ↗

PubChem computed values are shown separately from the ChEBI record. An exact InChIKey match was used to connect the records. Molecular descriptors do not describe a supplied product’s purity, particle size or performance.

Names & structural identifiers

Copy any identifier
L-cystine
(2R,2'R)-3,3'-disulfanediylbis(2-aminopropanoic acid)
LEVWYRKDKASIDU-IMJSIDKUSA-N
N[C@@H](CSSC[C@H](N)C(=O)O)C(=O)O
InChI=1S/C6H12N2O4S2/c7-3(5(9)10)1-13-14-2-4(8)6(11)12/h3-4H,1-2,7-8H2,(H,9,10)(H,11,12)/t3-,4-/m0/s1

Names & synonyms

(2R,2'R)-3,3'-disulfanediylbis(2-aminopropanoic acid)

Names are supplied by ChEBI. Trade names and related synonyms may describe a broader product context.

Classification & relationships

ChEBI ontology
cystineChEBI parent class · 17376 ↗non-proteinogenic L-alpha-amino acidChEBI parent class · 83822 ↗L-cysteine derivativeChEBI parent class · 83824 ↗
carboxylic acidamino acidorganosulfur compoundorganic molecular entity

Roles recorded in ChEBI

EC 1.2.1.11 (aspartate-semialdehyde dehydrogenase) inhibitorflour treatment agentmouse metaboliteSaccharomyces cerevisiae metabolitehuman metabolite

Database role annotations describe reported biological or chemical roles; they are not product approvals or recommendations for use.

Mass ↔ amount of substance

Calculated from sourced mass
Equivalent amount
0.00416136 mol

Uses 240.306 g/mol from ChEBI. Assumes the substance described by this record; no purity or concentration correction is applied.

Elemental composition

Theoretical mass fractions
C
Carbon · 6 atoms
29.99%
S
Sulfur · 2 atoms
26.69%
O
Oxygen · 4 atoms
26.63%
N
Nitrogen · 2 atoms
11.66%
H
Hydrogen · 12 atoms
5.03%

Calculated theoretical mass fractions from the reported formula and PubChem periodic-table atomic masses. These are not assay or purity results.

Research & patent references

Selected source associations
L-cystine inhibits aspartate-beta-semialdehyde dehydrogenase by covalently binding to the essential 135Cys of the enzyme. ↗Biochimica et biophysica acta · 2004 Jan 14 · PMID 14726201
Kosmotoga pacifica sp. nov., a thermophilic chemoorganoheterotrophic bacterium isolated from an East Pacific hydrothermal sediment. ↗Extremophiles : life under extreme conditions · 2014 Jan · PMID 24264736
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Sources & record history

Checked 27 Sep 2026
EMBL-EBI ChEBI · CHEBI:16283

Release 255, 9 September 2026. ChEBI three-star (manually annotated) source entry. View original record ↗ · CC BY 4.0

NCBI PubChem · CID 67678 · retrieved 2026-09-27

PubCAS formats source data, connects references and computes explicitly labelled conversions. CAS cross-references are supplied by ChEBI; they do not constitute CAS verification or endorsement.

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