---
title: "Cysteine: research glossary | Sable Peptides"
description: "Cysteine (three-letter code Cys, one-letter code C) is an amino acid with a thiol side chain that can form disulfide bonds with another cysteine. Cysteine"
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publisher: Sable Peptides Limited (UK company 17488610)
note: Research use only. Not for human or veterinary use.
---

Glossary

# Cysteine

Cysteine (three-letter code Cys, one-letter code C) is an amino acid with a thiol side chain that can form disulfide bonds with another cysteine. Cysteine is prone to oxidation and racemisation during synthesis. It is commonly protected with a trityl group in Fmoc chemistry and is used for site-specific conjugation.

Source: [en.wikipedia.org](https://en.wikipedia.org/wiki/Cysteine)

## Related terms

-   [Amino acid](/glossary/amino-acid)
-   [Racemisation](/glossary/racemisation)
-   [Oxidation](/glossary/oxidation)
-   [One-letter code](/glossary/one-letter-code)
-   [Conjugation](/glossary/conjugation)

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