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Molecule

Cysteine

L-cysteine

Cysteine is a sulfur-containing amino acid. Its reactive thiol group can form a covalent link with another cysteine.

Overview

EXPLORE BY LEVEL

Cysteine is a sulfur-containing . Its reactive thiol group can form a covalent link with another cysteine.

Quick Facts

AT A GLANCE
One-letter codeC
Three-letter codeCys
Chemical formulaC₃H₇NO₂S
Side chainThiol group (–CH₂–SH)
Show 3 more facts
Side-chain chemistrySulfur-containing; polarizable and usually uncharged
Human dietary contextUsually synthesized; can become conditionally essential, including when methionine supply is limited
Protein-building setOne of the 20 standard protein-building amino acids

Follow the Connections

See how Cysteine links to other biological records.

Open network
ConceptAmino AcidsincludesProcessTranslationincorporated during
All 2 Structured Connections
Amino Acids · ConceptINCLUDES →Cysteine · Molecule
Cysteine · MoleculeINCORPORATED DURING →Translation · Process

Recommended Reading

Trusted references for learning more about Cysteine.

textbookChemical Components of a CellMolecular Biology of the Cell · NCBI Bookshelf textbookFrom RNA to proteinMolecular Biology of the Cell · NCBI Bookshelf
Research Claims

Cysteine is a standard amino acid commonly used to build proteins.

Cysteine uses the residue codes Cys and C.