SHEET /m/cysteine · PubChem CID 5862 · CAS 52-90-4 · REV 2026.07
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Cysteine
from sourceC3H7NO2S · 121.16 g/mol
L-Cys · beta-Mercaptoalanine · Half-cystine · Cisteinum
What is Cysteine?
The amino acid whose sulfur atoms form the disulfide bridges that hold a protein's shape. It is what a perm breaks and re-forms in hair. from source
CategoryBody
Fig. 1 · 2D structure RDKit
SMILES
C([C@@H](C(=O)O)N)SWhere you'll find it
Your own body makes this one. It is not an ingredient you buy. See the rest of the body group.
Relative acute toxicity from source
Animal study data · LD50
- Reported LD50
- 1,890 mg/kg · low toxicity
- Species
- rat
- Route
- oral
An LD50 describes acute toxicity under experimental conditions and is not a safe or dangerous dose for a person.
Toxicity & hazards
Toxicity · LD50
1,890 mg/kg · low toxicity · LD50 rat oral from source
3 more reported values
- 1,550 mg/kgLD50 · other · rat
- 1,620 mg/kgLD50 · other · rat
- 2,000 mg/kgLD50 · dermal · rat
WarningIrritantH302, H315, H319, H335from source
Keep roaming
Where Cysteine leads
Relatedcomputed
Homocysteine62% similarBoth carry a carboxylic acid, an amine and a thiol group.Serine55% similarBoth carry a carboxylic acid and an amine group.Aspartic acid52% similarBoth carry a carboxylic acid and an amine group.Selenocysteine52% similarBoth carry a carboxylic acid and an amine group.Asparagine50% similarBoth carry a carboxylic acid and an amine group.Cystine50% similarBoth carry a carboxylic acid and an amine group.