nutrient
Cysteine
A sulfur-containing amino acid whose side chain can form disulfide bonds.
Educational draft · Human scientific and editorial review pending. About review status
Cysteine contributes sulfur to proteins and to oxidation–reduction chemistry.
How it works
A bond that can stabilise proteins
Two cysteine side chains can join to form a disulfide bond, helping stabilise selected folded proteins.
Related topics
Cysteine is used to build Protein
Cysteine is one of the amino acids used to assemble proteins.
Evidence: Established · Source checked 2026-09-05 · Sources: NIH National Library of Medicine: Biochemistry, Essential Amino Acids
Worth knowing
It is linked to methionine metabolism. Methionine and cysteine are the principal sulfur-containing amino acids.
A closer look
Its sulfur changes with redox conditions
The thiol group can switch between reduced and oxidised forms, so cysteine chemistry depends on its local redox environment.
Redox state matters
The thiol group can switch between reduced and oxidised forms, so cysteine chemistry depends on the local redox environment.
References
Source-checked local draft.
Human editorial review pending.
- NIH National Library of Medicine (opens in new tab)Biochemistry, Essential Amino AcidsChecked 2026-09-05
- NIH National Library of Medicine (opens in new tab)Biochemistry, Protein CatabolismChecked 2026-09-05
- NIH National Library of Medicine (opens in new tab)Biochemistry, Primary Protein StructureChecked 2026-09-05
- NIH National Library of Medicine (opens in new tab)Biochemistry, Collagen SynthesisChecked 2026-09-05